Deborah Hinnen, ANP, BC-ADM, CDE, FAAN, FAADE,1 and Richard A. Guthrie, MD, FACE2
1Hinnen is an advanced practice nurse and certified diabetes educator at Memorial Hospital’s Outpatient Diabetes Center, University of Colorado Health, Colorado Springs, CO. 2Guthrie is president of Great Plains Diabetes Research, Inc.; collaborating physician for Belinda Childs, ARPN; and professor emeritus at the University of Kansas Medical School-Wichita, Wichita, KS.
The essence of diabetes self-management is problem solving, detecting patterns, and making proactive changes in the food plan, physical activity, or medication protocols.1 These are advanced skills for people with diabetes. First, the basic self-care skills for diabetes management must be mastered, including glucose monitoring, insulin injection and oral medication dosing and timing, hypoglycemia prevention and treatment, daily schedule delineation, basic meal planning, and knowing when to call the practitioner. As a component of continuous, lifelong outpatient diabetes education, all nurses working with people with diabetes should be able to teach, reinforce, and verify these daily care activities.
Self-management of diabetes requires that people have essential information to make changes to their treatment regimen to achieve optimal control of diabetes. Technological advances have been significant over the past two decades in glucose monitoring, data analysis, and insulin delivery systems. The introduction of self-monitoring of blood glucose (SMBG) in the late 1970s replaced retrospective urine glucose testing methods. The benefits of frequent blood glucose monitoring were seen in the Diabetes Control and Complications Trial, which verified that glucose control could be achieved with intensive management.
Continuous glucose monitoring (CGM) is a growing technology that provides hundreds of glucose values per day. An emerging approach to help analyze that overwhelming amount of data is the average glucose profile (AGP).2
CGM uses an enzyme-coated sensor, placed by the patient in the interstitial tissue that monitors glucose on a continuous basis. The values are transmitted to a receiver that shows current glucose level with arrows up or down to indicate directional change. Graphs of the past several hours or 24 h allow patients to assess trends and make various adjustments to improve their glucose control. Glucose values transmitted directly to the continuous subcutaneous insulin infusion (CSII) insulin pump integrate data to the computer to ensure information is available seamlessly for making mealtime insulin dosing decisions or corrections. While improving, current insurance reimbursement is not optimal, contributing to the modest usage of CGM.
For people with diabetes not using a pump, technology currently is available that simultaneously transmit fingerstick glucose values to a smartphone and could be accessed or stored on the cloud. Data can be accessed and analyzed by family and providers as authorized by the person with diabetes. This eliminates a common problem of not having the meter or logbook available for office visits. An additional technology for nonpump users is the bolus calculator. This is a glucose monitor similar to insulin pumps that analyzes current glucose fingerstick data and gives recommendations on insulin dosing.3
The ultimate goal of diabetes management for insulin-requiring people is to be able to continuously collect glucose data, feed that into an insulin delivery system, and then have insulin automatically delivered as needed, thus creating a closed loop. At this point, the closed loop system is not available. However, “low glucose suspend” is available with a CSII device if glucose levels are too low. Until the complete closed-loop technology is perfected, the individual using CSII still must “pull the trigger” on insulin delivery or dose changes. Technology is changing rapidly but still requires an engaged individual or caregiver.
Most people who take insulin, not being able to access or afford the pump or sensor technology, and the even larger number of patients taking oral agents and injectable therapies, must manage the process of analyzing logbooks or downloaded data. This chapter provides solutions to problems faced by people with diabetes who are not utilizing data management software.
Practical Point
Adult learners learn best by experiential learning. Learning a skill such as glucose monitoring and analyzing that data is a hands-on activity that must include a return demonstration to verify the patient’s ability to obtain accurate results and verify critical-thinking skills.
GLUCOSE MONITORING
Glucose monitoring is the first step in the empowered patient’s role of being a self-manager. It is probably the most important part of being able to problem solve and manage diabetes on a daily basis. Monitoring provides feedback on changes in food intake, physical activity, medications, and daily living. SMBG allows patients to make changes in their everyday regimens and gives them immediate information about how different factors affect their glycemic control.
Blood glucose monitoring is primarily done with a blood glucose meter. However, CMS has just approved CGM (DexCom G5) as durable medical equipment (DME). This change should make CGM very accessible for Medicare patients. Most people with diabetes are currently using a fingerstick glucose meter. The choice of a blood glucose meter should be based on several factors.
Matching Meter to Patient
Following are the facts on modern glucose meters:
• Most meters are essentially accurate if the manufacturer’s instructions are followed.
• All newer meters are plasma referenced, which makes them comparable to the hospital and practitioner’s office results.
• Modern meters require a minimal amount of blood.
• Most meters have a capillary “sipping” action, drawing in a precise amount of blood.
• Most meters are smaller than a deck of cards.
• Meters have varying degrees of memory (10–3,000 data points).
• Most meters provide results in about 5 sec.
• Some meters have internal technology or software to help summarize the data.
Some meters bluetooth the data to a smartphone, the cloud, and now a portal for both patient and provider viewing.
• Manufacturers have comparably priced test strips.
• Medicare price bidding and high deductibles in health insurance have forced dramatic changes in meter and strip availability.
• It is more difficult to obtain sample meters for patients than in the past, and sample test strips are rarely available.
Given these facts, consider the following when helping a patient choose a meter:
• Does the patient have insurance coverage for strips and supplies?
—If not, review consumer reports data or refer the patient to a social worker or to local resources for purchasing strips at a reduced rate.
—Consider a generic-labeled, store-brand meter and test strips and less frequent but carefully staggered testing times.
• Does the insurance company have a preferred meter on formulary?
—If so, then recommend that meter.
—If there are no meter formulary restrictions, consider employment, lifestyle, and patient preference. For instance, people who are frequent computer users, piano players, or guitar players, may prefer alternate site testing (forearm, heel of hand).
• Does the patient have good vision and dexterity?
—If not, consider a meter with strips in a drum or disc to reduce the need to open cans.
—Tech-savvy people may want a meter with extended memory, data storage, re-chargeable batteries, data management capabilities, and bluetooth capabilities. Seniors or those who want something simpler may want a meter that has fewer steps and a larger screen with better contrast.
Key Meter Skills to Teach
The following information should be covered when teaching patients meter skills:
• If the patient has never performed a capillary blood glucose test, do a test with a drop of control solution on the patient’s finger so the patient can see how simple it is to perform the test. This also verifies that the strips are good and simulates the actual test.
• Help the patient get an adequate-size blood sample.
—Washing hands in warm soapy water cleanses the skin and helps dilate the capillaries, making it easier to obtain the drop of blood. There is no need to use alcohol to clean the skin; alcohol only dries the skin and causes stinging if a puncture is done while the alcohol is wet. Alcohol causes hemolysis if it gets in the blood sample. If fingers are not clean and dry, this can affect test accuracy.
—If using an alternate site like the arm, rubbing may increase circulation to the site.
—Select a finger that does not have calluses.
—Ask the patient to hang the hand in a dependent position for 30–60 sec and shake it (as if shaking down a thermometer) or snap the fingers to increase blood flow.
—Puncture on the side of the finger, not the tip. After the puncture, gently milk (rather than squeeze) the finger, from the base of the finger to the fingertip.
—If not enough blood is obtained, adjust the lancing device depth (bigger number = deeper penetration). Very few test strips allow for reapplication of the blood if enough is not applied the first time.
• The patient’s return demonstration will help identify mistakes.
• Provide the toll-free customer service number (normally found on the back of the meter or on the packaging) for assistance with such tasks as setting the date and time or changing the code.
• If working with inpatients, encourage self-management by having patients perform their own blood glucose test on their own meter during routine testing time. Patients can measure their blood glucose levels and compare those values with results obtained from the laboratory. The values should be within 10–15% of each other.
• Teach patients to carefully dispose of test strips and lancets in a container, not the trash.
• Disposal guidelines for sharps may vary from state to state. Find out what precautions need to be taken in your state.
• During an office visit, have the patient do a blood glucose test. Even those with longstanding diabetes may have technical issues.
Common User Errors and Corrective Actions
For common user errors and the ways to prevent or correct them, see Table 8.1.
Table 8.1—Common User Errors and Corrective Actions
|
Error |
Correction |
|
Not enough blood |
Use deeper penetration of lancet. |
|
Blood not adequately filling the test strip chamber |
Make sure blood touches strip and is held there until strip chamber is filled. May require more blood. |
|
Meter not calibrated to current strips |
Teach patients to calibrate strips every time they open a new vial or box of strips. |
|
Ruined strips, strips that have been out of the container for too long, out of date, or mail-order strips that got too hot or cold |
Open a new box or vial of strips. Teach patients not to store strips out of the container. |
|
Not using control solution to check test strips or using control solutions that are too old |
Teach patients to use control solution to ensure the strips are reading accurately. Date control solution when opened and discard after 90 days (even if date on box is current). |
Motivating Reluctant Testers
• Have patients experiment with blood glucose testing before and after certain foods or their favorite meal, for example, cereal and a glass of orange juice at breakfast, a meal with dessert, or a fast-food meal (e.g., hamburger, fries, and soft drink).
• Many patients have symptoms that are nonspecific and describe it as “feeling funny.” Tell patients to test when they feel “funny” to see whether the symptoms are attributable to their blood glucose levels. Sometimes those feelings can be a sign of something other than diabetes (e.g., heart problems, hypertension). It is difficult to discern hypoglycemia from a myocardial infarction in people with diabetes. If a patient has low blood glucose with chest pain or other symptoms, and those symptoms are relieved with treatment for the hypoglycemia, the symptoms are likely those of hypoglycemia. It is important, however, to teach patients how to respond to symptoms that are not resolved by treatment for hypoglycemia. It is often reassuring for patients to be able to attribute those “funny feelings” to a glucose value.
• Ask a patient to speak at a diabetes support group meeting at which he or she can share their experiences, show new patients how to keep a logbook, download their meter, and lead a discussion of pattern recognition and problem solving.
• Negotiate with someone else at home to do the testing for 1 week.
• Negotiate the testing frequency based on what the patient is willing and able to do. Doing a seven-point glucose profile for 3 days, and then taking several weeks off, provides enough data for pattern management and provides a break from frequent testing for patients with type 2 diabetes (T2D).4
• Negotiate weekly data review with the patient by fax, phone, or e-mail.
Glucose Monitoring Schedules
Patients who use insulin are often asked to test three or more times per day: fasting and premeal or 2 h after each meal, and sometimes between 2:00 and 3:00 a.m. The American Diabetes Association (the Association) recommends that postprandial testing may be appropriate to achieve postprandial glucose targets, but that “the frequency and timing of SMBG should be dictated by the particular needs and goals of the patients.”4 In patients with T2D who are not being treated with insulin, some regimen of SMBG may correlate with a reduction in glycated hemoglobin A1c (A1C); however, other factors, such as diet and exercise counseling or other pharmacological intervention, make it difficult to assess the contribution of SMBG alone.5–8
Pre- and postprandial testing allows for the calculation of glycemic excursions. Glycemic variability research suggests that the excursion, or variable “swing in glucose >50 mg/dL after meals,” triggers reactive oxidative stress, which has been implicated in both micro- and macrovascular complications of diabetes.8 Once glycemic goals have been reached in patients with T2D, testing may be less frequent (four times per day, 3–4 days per week or one time per day at alternating times). People who count their carbohydrate intake and determine their insulin dose using insulin-to-carbohydrate ratios will test before meals to determine how much insulin to take for the meal. Women who are pregnant and people using insulin pumps are asked to test every day, four to six times per day.
People using oral agents may test less often after reaching glycemic goals. Little consensus guides home blood glucose testing schedules or frequency in those who use oral medications for their diabetes. The International Diabetes Federation SMBG guidelines for patients with T2D provides well-documented rationale and options for testing with this important population.9 If the person is insured by Medicare, 100 test strips for a 3-month period are covered. This dictates testing frequency to a great degree. If people choose to test their glucose level daily either fasting (once daily) or fasting and at 4:00 p.m. (twice daily), they will miss postprandial glucose excursions. Therefore, alternating days and times during the day to provide a more complete glucose pattern would be a better use of testing supplies. Consequently, testing four times per day, 2 days per week is the recommendation for many people on oral agents.1,10–11Some practitioners recommend testing two times per day, 4 days per week. Individualization is the key to successful testing. For instance:
• Patients may need more blood glucose tests during illness, medication changes, dietary changes, and stress.1
• During acute illness, premeal or hourly testing is needed to determine the need for and specific dose of any supplemental rapid-acting insulin.
• Asymptomatic hypoglycemia (i.e., hypoglycemia unawareness) requires more frequent and regular testing on a daily basis, particularly at peak insulin times and before driving, as a precaution for identifying low blood glucose levels.
• Pregnancy requires frequent SMBG (i.e., five to seven times per day, every day) to make the adjustments needed to optimize blood glucose control (Table 8.2).
Table 8.2—Summary of Glycemic Recommendations for Many Nonpregnant Adults with Diabetes
|
A1C |
<7.0% (53 mmol/mol)* |
|
Preprandial capillary plasma glucose |
80–130 mg/dL* (4.4–7.2 mmol/L) |
|
Peak postprandial capillary plasma glucose† |
<180mg/dL* (10.0 mmol/L) |
*More or less stringent glycemic goals may be appropriate for individual patients. Goals should be individualized based on duration of diabetes, age/life expectancy, comorbid conditions, known CVD or advanced microvascular complications, hypoglycemia unawareness, and individual patient considerations.
†Postprandial glucose may be targeted if A1C goals are not met despite reaching preprandial glucose goals. Postprandial glucose measurements should be made 1–2 h after the beginning of the meal, generally peak levels in patients with diabetes.
Source: From the American Diabetes Association.4
Other Measures of Glucose Control
A1C
The gold standard in overall diabetes control remains the A1C level. This measure of control provides an average (or weighted mean) of the blood glucose level over the past 2–3 months. The glycation process, in which glucose attaches to the hemoglobin molecule, is irreversible and linear, with higher glucose levels causing increased glycation, thus higher A1C values. Therefore, A1C provides a picture of the average blood glucose level during the 120-day life span of the hemoglobin molecule. To help patients understand this concept, think of a doughnut (the red blood cell), with frosting (if glucose has been very high), and sprinkles (if extremely high).
The Association has effectively promoted a standardization process for the A1C.12 High-performance liquid chromatography and immunoassay methods now commonly are used to measure A1C. The normal range is 4–6%. With consistency from hospital, clinic, and physician laboratories, this test and the anticipated normal ranges allow practitioners to speak a common language in regard to diabetes control.
Estimated Average Glucose
The correlation of average glucose to the long-term measurement of glycated hemoglobin has been determined through a large study using CGM and SMBG in people with T1D, T2D, or no diabetes.13
Many pharmaceutical companies and the Association on its website provide teaching materials, charts, and calculators to explain the relationship of a normal A1C value of 6% to a correlated average glucose of 126 mg/dL (7 mmol/L) for the past 2–3 months. As the A1C value goes up 1 percentage point, the glucose averages go up ~28.7 mg/dL (1.6 mmol/L). Consequently, an A1C of 7% equals an average glucose of 154 mg/dL (8.6 mmol/L) (See Table 8.3).
Table 8.3—Estimated Average Glucose (eAG)
|
mg/dL* |
mmol/L† |
|
|
A1C (%) |
||
|
5 |
97 (76–120) |
5.4 (4.2–6.7) |
|
6 |
126 (100–152) |
7.0 (5.5–8.5) |
|
7 |
154 (123–185) |
8.6 (6.8–10.3) |
|
8 |
183 (147–217) |
10.2 (8.1–12.1) |
|
9 |
212 (170–249) |
11.8 (9.4–13.9) |
|
10 |
240 (193–282) |
13.4 (10.7–15.7) |
|
11 |
269 (217–314) |
14.9 (12.0–17.5) |
|
12 |
298 (240–347) |
16.5 (13.3–19.3) |
Data in parentheses are 95% confidence intervals.
*Linear regression eAG (mg/dL) = 28.7 × A1C − 46.7. †Linear regression eAG(mmol/l) = 1.59 × A1C − 2.59.
Source: Reprinted with permission from Nathan et al.13
The Association’s Standards of Medical Care in Diabetes generally recommend an A1C goal <7% (corresponding to average blood glucose values of <154 mg/dL [8.6 mmol/L] with individualization of glycemic targets.2Testing should be done every 3 months (or 91 days for Medicare) until glycemic goals are reached and then every 6 months. The recommendation to take action if the value is >7% is critical to the prevention of long-term complications of diabetes.
According to the Association, the A1C goals should be individualized based on duration of diabetes, pregnancy status, age, comorbid conditions, hypoglycemia unawareness, and other individual patient considerations. More stringent glycemic goals may be appropriate in some individuals if this can be achieved without risk of hypoglycemia. Conversely, less stringent goals than <7% may be appropriate for patients with limited life expectancy, advanced microvascular complications, poor support, few resources, or cardiovascular disease or those with a history of severe hypoglycemia.4 Individualizing glycemic goals is recommended by the Association, the American Association of Clinical Endocrinologists, and the European Association for the Study of Diabetes (EASD).
Glycemic variability suggests that managing A1C alone may not be enough to prevent long-term complications of diabetes. Glycemic extremes trigger reactive oxidative stress, which initiates a cascade of events that lead to micro- and macrovascular damage. Postprandial variability is associated with an increase in carotid intima-media thickness, which is a clinical marker for atherosclerosis.8,14
Analyzing glucose records to determine and minimize glycemic variability is gaining importance. The downloadable printouts from glucose meters and CGM systems are reporting more statistics than just averages and number of tests per time period. Evaluating glycemic variability can be accomplished by reviewing such summary data from glucose meter and sensor downloads as follows:
• Mean blood glucose: This represents an average during a specific time period (e.g., average of fasting glucoses, average after breakfast glucose values).
• Standard deviation: This is an indicator of extremes of glucose levels. It is a representation of the highest and lowest blood glucose levels in a time period or of the total number of glucose tests. If mean glucose is near the goal, clinicians suggest that two times standard deviation should be less than the mean. For example, if the average glucose is 139 mg and the standard deviation is 45, then two times the standard deviation (45 × 2 = 90) is less than the mean (90 < 139).
• Median: The median is the middle point of the distribution of values (i.e., half of the values are above and half are below that point).
• MAGE: This is the mean amplitude of glycemic excursion, or the area under the curve. This method evaluates how high the glucose level is and how long it has been above target.
Additional information may include the low blood glucose index, high blood glucose index, or average daily risk range.
The Average Glucose Profile
The AGP is another way to obtain summary data. While still in development, it will be able to summarize data from any CGM system. Predictive low and high areas may be documented on screens and printouts as well. This emerging data analysis system may help providers deal with data overload in an effective way.2
FDA has recently agreed that “time in target” is another useful way to verify glucose control level.
Fructosamine: Glycated Albumin
The glycation of serum albumin is a process similar to the glycation of hemoglobin. The result, however, provides a glucose average of the past 10 days. Conceptually, this would be valuable for medication adjustment. Fructosamine would be especially useful in situations in which short-term measurements are needed, such as in pregnant women, elderly patients, or patients unable to do SMBG. Fructosamine also may be helpful in patients with hemoglobinopathies, for whom the A1C may not be accurate.
Normal ranges vary with the different methods used. This test is not as standardized as the A1C. The lack of standardization of the testing procedure has limited the use of this measure.
Ketone Testing
Ketone testing provides an important indicator of fat metabolism and free fatty acid conversion in the liver. In the face of hyperglycemia, this is an indication of insulin insufficiency and alternative fuel availability. Fat is used for fuel and the byproducts are called ketone bodies which build up in the blood. There are three ketone bodies. Acetoacetate is created first. Beta-hydroxybutyrate is created from acetoacetate. Acetone is a spontaneously created side product of acetoacetate. Beta-hydroxybutyrate is the predominant ketone body present in severe diabetic ketoacidosis (DKA). The accumulation of these acids decreases the pH and eventually leads to DKA. Therefore, it is important to test for ketones when glucose levels are elevated and especially during illness.
Ketones can be tested by a urine dipstick or plasma testing for δ-hydroxybutyric acid with the blood ketone meters. Urine ketone testing is done by dipping a ketone test strip into a urine sample and comparing it with the color chart in the appropriate time period advised by the manufacturer.
Ketones are rarely present in patients with T2D because these patients still have endogenous insulin production. If patients have lost weight because of inadequate calorie intake, ketones likely will be present. On sick days, however, counterregulatory hormones and catecholamines may trigger ketosis in patients with T2D as well as in those with T1D. Therefore, all people with diabetes need to test for ketones when they are ill. In pregnant women, ketones and hyperglycemia (DKA specifically) during the first trimester are incompatible with fetal viability. Later in the pregnancy, positive ketones are usually an indication of a hypocaloric situation called starvation ketosis. This often can be rectified with the addition of a bedtime snack containing complex carbohydrate.
Following are indications for ketone testing:
• When blood glucose levels >250–300 mg/dL (13.9–16.6 mmol/L), especially in patients with T1D.
• During illness.
• When fasting, during pregnancy.
• If glucose levels >150 mg/dL (8.3 mmol/L) during pregnancy.
PROBLEM SOLVING AND SELF-MANAGEMENT
Concepts of Pattern Management
Pattern management is a comprehensive approach to blood glucose management that includes all aspects of current diabetes therapy.1,15–18 Although this approach typically is identified with intensive or flexible insulin therapy, pattern management also should include changes in nonpharmacological therapies (i.e., nutrition therapy and physical activity) and combinations of oral agents or injectables to improve glycemic control.
Elements of pattern management include the following:
• The motivation on the part of the person with diabetes to be an active participant in care
• Individualized blood glucose goals negotiated by the person with diabetes and the diabetes care team
• Frequent SMBG or CGM recorded in a logbook or with software, to provide data for making adjustments
• A food plan to follow, starting with eating consistent amounts of calories and carbohydrates as a basic skill. An advanced skill would be to determine insulin-to-carbohydrate ratios (developed by measuring the usual amount of insulin needed to cover varying amounts of carbohydrate), which are used for adjusting the insulin dose based on carbohydrate intake19
• Multiple injections of insulin, insulin pump therapy, or combinations of oral agents, injectables, and insulin
• Self-adjustments, based on blood glucose monitoring data, food intake, physical activity, and medications to achieve glycemic goals
• Frequent interaction between individuals with diabetes and the diabetes care team, using telephone, fax, and e-mail to discuss glucose values between visits
• Comprehensive self-management training, including the following:
—Coverage of the education content areas identified by the National Standards for Diabetes Self-Management Education20
—The relationship of glucose levels, food, activity, and medications
—Prevention of hypoglycemia or hyperglycemia
—Sick-day management
—Purpose, strategies, and value of pattern management for intensive therapy to achieve blood glucose goals
—Empowerment of the patient through education for decision-making and problem solving, goal setting, and long-term motivation
—An understanding of the personal belief systems related to the value of health and intensive diabetes management
—Access to diabetes and health-related supplies
—Support systems to provide emotional and clinical management support
—Diabetes care team with on-call clinical support
—Ongoing education, such as support groups offered via the Association, hospital, or education center20,21
STRATEGIES FOR PATTERN MANAGEMENT
Pattern management involves reviewing several days of glucose records and making adjustments in diabetes treatment based on trends, rather than reacting to a single high or low blood glucose reading. Adding supplemental or sliding-scale insulin at the time of the elevated glucose level solves the problem only for that particular point in time but does not prevent the problem from occurring again.22–24 Effective pattern management takes into account all of the variables that affect blood glucose levels—including food, physical activity, stress, and illness—not just insulin or other medication adjustments.1
The patient must have a food plan that he or she can consistently follow. The person with diabetes, in consultation with a registered dietitian or CDE, should determine the number of calories or carbohydrate servings. To determine patterns, food intake, physical activity, and timing and doses of insulin or other medications must be as consistent as possible. This helps prevent blood glucose fluctuations that can mask true patterns.
In individuals using insulin, if blood glucose levels are out of goal range, consider whether the individual prefers to change calorie or carbohydrate intake, change physical activity, or make adjustments in insulin or other medications. Although it is easier to make insulin or other medication adjustments, weight management must be a consideration. Increasing insulin to cover extra food or carbohydrates will anabolically store total calories and potentially increase weight. Additionally, consider whether the individual is on enough insulin, too much insulin, or the wrong insulin regimen.25–28
In individuals with T2D, if blood glucose levels are out of goal range, consider whether the individual
• has a food plan that he or she is able to follow,
• requires a change in medication dose,
• requires the addition of other diabetes medications,29
• requires the addition of evening insulin, or
• requires a change to a comprehensive insulin-only regimen.
The first step in pattern management is to identify blood glucose trends in relation to glucose goals. The individual with diabetes needs to provide multiple data points at critical times for evaluation and problem solving and to collect sufficient data to evaluate whether goals are being met. Ideally, this means monitoring four to seven times a day, but adequate data can be obtained by testing four times a day, 2 or 3 days per week or testing two times per day, at alternating times, for 1 or 2 weeks. Food records with the number of calories and carbohydrate servings compared with blood glucose readings then can be analyzed once or twice a week.
When looking for patterns, read down the columns of blood glucose records to review all of the readings at the same time of day (e.g., fasting). A sample blood glucose record is provided in Table 8.4. Three high readings at the same time each day show a pattern of high blood glucose levels. Several low readings at the same time show a pattern of low blood glucose levels. If blood glucose readings are high at a specific time for 3–5 days, that is a pattern. Potential causes for the elevated levels should be examined so that the problem can be corrected. Causes of high blood glucose levels can be any of the following:
• Eating too much carbohydrate or more calories than usual.
• Doing less physical activity than usual.
• Taking too little insulin, missing an insulin dose, or having problems with the dose, type, or combination of oral medications.
• Using expired or improperly stored insulin or not taking oral agents as prescribed.
• Experiencing emotional or physical stress, including illness.
• Having a rebound response from the liver releasing excessive amounts of glucose from glycogen as a result of hypoglycemia.
• Overtreating hypoglycemia.
Table 8.4—Sample Blood Glucose Log
|
Fasting blood |
After breakfast |
After lunch |
After supper |
|
|
Monday |
106 |
198 |
84 |
112 |
|
Tuesday |
159 |
210 |
178 |
191 |
|
Wednesday |
141 |
188 |
— |
113 |
|
Thursday |
139 |
222 |
132 |
233 |
If blood glucose levels are low for several days at the same time, potential causes should be examined. Low blood glucose levels usually are corrected before high levels. Untreated hypoglycemia can cause a rebound glucose response, induced by the counterregulatory hormone glucagon, with hyperglycemia to occur later. Causes of low blood glucose levels can be any of the following:
• Eating too little carbohydrate or less than usual (i.e., too few calories).
• Doing more physical activity than usual.
• Taking too much insulin or oral medication.
• Taking a hot bath or shower for an extended period of time.
Simply Put
For the well-educated patient, help them evaluate several days or weeks of glucose values for patterns of the following:
• Hypoglycemia; frequency more than 1–2 times per week
• Fasting hyperglycemia
• Postprandial hyperglycemia
Then, help the patient
• Evaluate the potential causes
• Make changes in food, exercise, and medications
• Reevaluate glucose levels the next week or two to verify the changes corrected the problem
Questions to Ask When Evaluating Blood Glucose Values
Consider the following questions when evaluation blood glucose values:
• Is there a pattern when evaluating 3–5 days of blood glucose readings?
• Does something happen at the same time every day, such as an insulin reaction or high glucose after breakfast?
• Do blood glucose readings represent all “times” of the day?
• Do blood glucose readings reflect the “peak” times of each medication (insulins or oral agents)?
• Do after-meal glucose values represent peak glucose values?
• Do “other notes” or “changes” account for observed patterns, such as meal times, carbohydrate or calorie variances, exercise changes, unusual hours of work or school, stress, or illness?
• Is prevention of weight gain or weight loss important for the patient? If so, consideration must be given to trying to reduce the use of hypoglycemic medications (i.e., insulin or insulin secretagogues), especially if low blood glucose levels are occurring routinely.
• Does the patient have a history of weight gain? Is the weight gain the result of overtreatment of frequent episodes of hypoglycemia?
• Does the patient have a history of weight loss? Is the weight loss caused by poor glycemic control?1
Interpreting Blood Glucose Readings for People Taking Insulin
Knowing what the glucose level means based on when the test was performed is critical to effective decision-making.
• Premeal glucose measurements are needed to monitor basal (or background) insulin doses (e.g., NPH, glargine, or detemir). If fasting or predinner readings are out of the target range, consider adjusting basal insulin doses. Premeal testing also may be used to determine whether a supplemental or correction insulin dose is needed to add or subtract from the bolus dose.
• 2-h postprandial glucose readings are needed to titrate rapid-acting insulin (e.g., lispro, aspart, glulisine) for mealtime injections. If the difference in premeal and postprandial glucose readings is >50 mg/dL (2.2 mmol/L), consider adjusting the mealtime rapid-acting insulin by 10%.30
• 2-h postprandial readings also are used to evaluate the effectiveness of many medications: incretins (GLP-1s: exenatide, liraglutide; DPP-4s: sitagliptin, saxagliptin, linigliptin, alogliptin; thiazolidinediones, secretagogues: glimepiride, glipizide, glyburide, repaglinide, nateglinide, α-glucosidase inhibitors; and other glucose-lowering agents).
• 2-h postprandial glucose testing is helpful in patients with T2D who are not taking any of the previously noted medications to evaluate their pancreas first-phase insulin release (i.e., when evaluating the effect of meals and certain foods on blood glucose levels).29
• Elevated fasting glucose levels may require 3:00 a.m. testing and recording at least once or twice a week to determine the cause. High fasting glucose levels can be caused by any of the following:
—Overnight hypoglycemia that triggers the liver to release glucose (Somogyi or rebound effect), most likely in T1D
—Normal hormonal changes that trigger the liver to release excessive glucose in the early morning (dawn phenomenon)
—Insufficient basal or background insulin
—In youth, growth hormone secreted at night during growth spurts
—Excessive hepatic glucose release, most likely in T2D
Interpreting CGM Data
Individuals with diabetes who are using CGM and providers alike will find that they need to change how they think when evaluating CGM data. This is a rapidly evolving science. FDA has recently removed the “adjunctive” requirement, thus allowing people to dose insulin based on the results of their glucose sensor. Individuals were using CGM as adjunctive therapy with multiple daily injections, integrated with insulin pumps. Now as part of a hybrid closed loop system like the MiniMed 670G, individuals have real-time data to evaluate continuously and can make decisions on the spot, but they must remember that a lag time may exist between the interstitial glucose and the capillary glucose.31 Trending arrows indicating rapid increases or decreases in the glucose are becoming more valuable for insulin corrections than ever before. New treatment targets for the patient may need to be set with guidance from the provider. Alarms should be set at higher than usual targets (e.g., not at 55 mg/dL but at 70 mg/dL or 80 mg/dL) to alert the individual that glucose is low or predictive alerts to indicate “drops.” Predictive alerts draw attention to rapidly rising and falling glucose levels. This allows the individual to be proactive rather than reactive. Learning to respond to trends rather than responding to a single number is important. In fact, this is the primary benefit in CGM identified by many people using the technology.
Because it is real-time data, it is easy to treat the current blood glucose without taking the time to evaluate the daily patterns that may evolve. Individuals can use the event markers to record information about meals, insulin doses, and other events. The individual then can look for patterns based on these events. Potential changes may include timing of the bolus doses, amount of the bolus doses, amount of the basal insulin, and changes in the insulin-to-glucose correction dose.32 It is important that patients be able to use the software program that comes with their CGM system to analyze the data. The software allows patients and providers to evaluate the glucose information continuously, hourly, in time blocks, by meals, by days of the week, by weekend, or by weekday. Individual time blocks can be set by the provider with the patient or solely by the patient. Any number of days—up to 60 on some programs—can be “overlaid” and the trend can be identified. The median and the standard deviation for various times may be more important than an average.
Chapter 26 Diabetes Technologies has additional information regarding insulin pumps and CGM.
A Case in Problem Solving: John
John is a 57-year-old man who has had T2D for 5 years. He works as a manager at Wal-Mart and has no known complications. John is taking the following diabetes medications:
• Morning: 10 mg glipizide, 1,000 mg metformin XR
• Evening: 10 mg glipizide, 1,000 mg metformin XR
His food plan consists of 1,800 calories.
|
Monday |
Saturday |
||
|
Glucose values (mg/dL) |
|||
|
Fasting |
187 |
199 |
203 |
|
2 h after breakfast |
139 |
144 |
148 |
|
Before lunch |
|||
|
2 h after lunch |
152 |
133 |
121 |
|
Before dinner |
|||
|
2 h after dinner |
128 |
146 |
138 |
Changes in schedule/routine:
Diet
Insulin/medication
Reactions
Activity
Problem: High fasting blood glucose levels
Possible cause: Inadequate medication in evening or at bedtime to prevent excessive hepatic glucose release
Options:
• Assure John that the high fasting glucose levels likely are not because he ate too much at dinner or during the evening. Explain that food that is eaten is used or stored in 4–5 h. Explain how the liver releases excessive glucose in the early morning hours if adequate insulin is not available.
• Consider adding glucagon-like peptide-1 (GLP-1): exenatide (Byetta/Bydureon), liraglutide (Victoza), dulaglutide (Trulicity), albiglutide (Tanzeum), or bedtime NPH or a glargine or detemir insulin dose (initiate bedtime basal dose at 10% of total body weight).
• Consider adding a third oral agent, such as a sodium-glucose co-transporter (SGLT): canagliflozin (Invokana), dapagliflozin (Farxiga), or empagliflozin (Jardiance), or a small dose of pioglitazone (e.g., 15 mg).
A Case in Problem Solving: Mary Jane
Mary Jane is a 40-year-old woman who has had type 1 diabetes (T1D) for 18 years. She works in a call center. Mary Jane has mild peripheral neuropathy in both feet, but no visual changes. Recently, she began a daily four-injection regimen to improve her glucose control.
• Breakfast: 12 units insulin lispro
• Lunch: 10 units insulin lispro
• Dinner: 14 units insulin lispro
• Bedtime: 40 units insulin glargine
Her food plan consists of 1,600 calories (three meals and one snack) with an additional 2 units insulin lispro for each additional carbohydrate choice (15 g) eaten (2:7 insulin-to-carbohydrate ratio).
|
Wednesday |
Friday |
Sunday |
|
|
Glucose values (mg/dL) |
|||
|
Fasting |
100 |
110 |
103 |
|
2 h after breakfast |
315 |
292 |
248 |
|
Before lunch |
|||
|
2 h after lunch |
269 |
233 |
149 |
|
Before dinner |
|||
|
2 h after dinner |
144 |
136 |
137 |
|
Changes in schedule/routine: |
|||
|
Food |
donut |
O.J., toast |
Pancakes |
|
Insulin/medications |
|||
|
Reactions |
|||
|
Activity |
Walk after lunch |
||
Problem: Pattern of high blood glucose levels after breakfast on 3 days and lunch on 2 days
Possible causes:
• Too much carbohydrate at breakfast or lunch for the current insulin dose
• Too many calories for breakfast
• Not enough insulin before breakfast or lunch
• Insulin-to-carbohydrate ratio is incorrect, needs to be recalculated
• Not counting carbohydrate correctly
• Not using insulin-to-carbohydrate ratio
Options: Consider changing something in routine before the high tests:
• Decrease total carbohydrate at breakfast or lunch.
• Change the composition of breakfast (i.e., reducing the carbs and adding protein and fat).
• Decrease total calories at breakfast or lunch.
• Increase the dose of insulin lispro before breakfast or lunch (e.g., by 10%).
• Increase the insulin-to-carbohydrate ratio at breakfast (e.g., 2:6; 2.5 units insulin lispro per carbohydrate serving).
• Include exercise after breakfast; it was effective on Sunday after lunch.
LIFESTYLE ISSUES
Self-management is central to integrating successful glycemic control with flexibility of lifestyle. Three common issues illustrate how this is done.
Traveling
Travel is not the cumbersome experience it once was for people with diabetes. Security issues have made it easier to travel with medical equipment. People with diabetes must familiarize themselves with the Transportation Security Association (TSA) and Federal Aviation Administration (FAA) guidelines. The information is summarized on the Association’s website (www.diabetes.org).
• It is recommended that all medications have the pharmacy label. The pharmacy label typically is applied to an insulin box, so advise individuals to save boxes, even from insulin pens. While this is recommended, it is not required. Declaring this is medicine is often enough.
• Meters and supplies can go through the security check without damage to the equipment. Pumps, however, should be disconnected for the short time needed to clear security. Pumps and CGM should not be sent through the magnetic screening. Review the manufacturer’s recommendations.
• On overseas flights, patients may order special meals, but airlines should be notified well in advance or during the purchase of tickets. Snacks often are not available on domestic flights. It is advisable to carry extra snacks when flying.
• All supplies (medication, testing supplies, items to treat hypoglycemia, and snacks) should be in a carry-on bag, not packed in checked luggage, so that temperature-sensitive supplies are protected and supplies are at hand.
• Documentation from a practitioner explaining that the person has diabetes and must carry various medications and supplies is not required by the FAA because of the increased risk of forgery. Some customs agents, however, accept such letters.
• Education on travel outside of the country should include arranging emergency medical contacts and knowing the phone numbers and address of the embassy.
• Instructions on acquiring medication if the traveler has his or her carry-on bag stolen should include going to the emergency room or pharmacy in that country. Insulin may be a different concentration—for example, U-40 (40 units/cc) or U-80 (80 units/cc) rather than U-100 (100 units/cc). The person can obtain that country’s “meal-bolus” insulin and “basal” insulin and syringes or pens to match. A unit of insulin is an international measure, but the dilution of the insulin will be variable. If the person needs 10 units of insulin lispro for lunch, he or she will need 10 units of regular (or other available rapid insulin) in U-80 or U-40 strength, drawn up in the appropriate U-80 or U-40 syringe. The amount will look different because of the dilution of the insulin.
• In the past, crossing time zones has been the greatest challenge for insulin users. The use of insulin glargine or detemir has made this much less difficult. Keep the injection time for glargine or detemir on the same schedule as in the patient’s original time zone. Other meal insulins may change to match the mealtimes of the new destination. People using insulin pumps may need to adjust the timing of their nighttime basal rates based on when they sleep in the new time zone. Flexibility in mealtimes continues to be a strength for those using pumps and multiple daily insulin.
• Keeping supplies from getting too hot is another consideration, whether flying or driving. Travel kits with cool gel packs are available from pharmacies for a reasonable cost. Insulated lunch bags also are useful for moderating temperatures. Insulins, however, are stable at room temperatures, <86°F; injectables <77°F for ~2–4 weeks.
• Traveling always requires that snacks and glucose for treating hypoglycemia be available and within reach at all times.
• Temperature control for supplies is a concern. People should not leave their emergency snacks or medication in the car, even when they go into a restaurant for lunch.
• Traveling to high altitudes may affect meter readings and reduce appetite. If skiing or hiking, the insulin dose may need to be reduced because of increased activity and lower caloric intake. Snacks and glucose should be carried in a pocket or backpack.
Drinking Alcohol
The literature is confusing regarding the benefits and risks of alcohol intake. For some, drinking alcohol may be harmful, particularly if taking certain medications. If the person with diabetes chooses to drink, however, the key is to understand the physiology and make informed decisions.
• Alcohol is detoxified in the liver, where the glycogen reserves are stored and normally released in case of hypoglycemia. At the time alcohol is consumed, glucose values likely will rise because of the carbohydrate in the beer, wine, or mixed drinks. The later and more dangerous effect of alcohol is a hypoglycemic effect. This hypoglycemic effect may take place anywhere from 8 to 20 h after drinking. If the person has had enough to drink and becomes hypoglycemic during the night while sleeping, the liver may not be able to release glycogen reserves to protect and correct the low blood glucose. This situation is potentially fatal.
• Drug interactions are known to occur with several oral agents.
—Sulfonylureas) may cause an Antabuse, or disulfiram, reaction when the person drinks. This will be evident by flushing and nausea.
—Binge drinking (defined by the ADA as five or more drinks on one occasion) while on metformin can increased lactate levels, potentially leading to lactic acidosis, and may be fatal. Flu-like symptoms may be a confusing side effect that also can occur with intoxication.
• For the person who chooses to drink, the key is moderation.
—If the person is in optimal glycemic control, the Association’s guidelines for alcohol intake suggest a maximum of one (for women) to two (for men) drinks per day.
—Alcohol should be consumed with food.
—Alcohol calories should be calculated into the total daily intake.
—Even if blood glucose values are elevated, the bedtime snack should not be skipped. That should include carbohydrate and protein.
DRIVING PRECAUTIONS
The Association published a workgroup report regarding diabetes and driving.33 States vary in their requirements regarding driving and diabetes. People with diabetes depend on their ability to maintain a driver’s license to carry out their daily living. Health-care providers need to remind individuals with diabetes to take precautions to be proactive to prevent hypoglycemia while driving.
Individuals with diabetes who were on insulin were once restricted from having a commercial license. Interstate and intrastate truck drivers can receive federal or state waivers, signed by an endocrinologist, to drive. Federal requirements can be obtained online34 at http://www.fmcsa.dot.gov/sites/fmcsa.dot.gov/files/docs/Diabetes_Exemption_Package0706.pdf.
It is prudent for all drivers on insulin or any antihyperglycemic agent that may lead to hypoglycemia to check blood glucose before driving. It is imperative if one has hypoglycemia unawareness that blood glucose should be monitored before driving. Drivers with diabetes must be counseled to always carry a blood glucose meter and appropriate snacks, including a quick-acting source of glucose. They never should begin an extended drive with low normal blood glucose (e.g., 70–90 mg/dL) without eating a snack. The individual should stop the vehicle as soon any of the symptoms of low blood glucose are experienced and measure and treat the blood glucose level. It is recommended that one not drive for 30–60 min after a low blood glucose because of the delay of cognitive function for 30–60 min.
SUMMARY
Monitoring for self-management is the standard of care for diabetes management. The technology, medications, and education available to people with diabetes and providers has vastly improved. These pieces of the puzzle, when put together in an organized fashion, create a picture of flexibility and optimal glycemic control that is clearer now than ever before. The elusive nature of diabetes care and glycemic control has been replaced with a sharper image—a clearly focused, detailed picture of diabetes management that is patient driven. Nurses can help patients take ownership in this intensive management approach.
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