Think Like a Pancreas

by Gary Scheiner

  Keep in mind that your diabetes records—including blood sugar levels—are simply pieces of information that you and your health care team can use to make competent decisions and fine-tune your management plan. These records are not meant to pass judgment on you as a person. As I tell many of my patients: “Any information is good information—regardless of the numbers.” When you look at your logs and downloaded reports, pretend you’re the health care provider evaluating someone else’s data. Don’t take anything too personally!

  Finally, memorize the Serenity Prayer. Don’t misunderstand: I am not a very religious person, but I do know when something makes sense. The Serenity Prayer reminds us that not everything is within our control. To fret over things beyond your control is a waste of time and effort. Instead, concentrate on the things you can control. We may not have the final say over what each blood sugar reading is, but we can improve our odds of a decent reading by doing the right things.

  A little bit of luck—or help from above—wouldn’t hurt either.

  THE SERENITY PRAYER

  God, grant me the serenity to accept the things

  I cannot change,

  the courage to change the things I can,

  and the wisdom to know the difference.

  Chapter Highlights___________________________________________

  •The HbA1c is an important test for assessing overall glycemic control.

  •Establish target glucose ranges based on your personal goals, and strive to hit the targets as often as possible.

  •Successful diabetes management requires proper tools, self-care skills, and the right attitude. One or two out of three won’t cut it—all three are necessary.

  •Self-management tools include appropriate insulin, an effective insulin-delivery device, a modern blood glucose monitoring system, and a supportive, multidisciplinary health care team.

  •Self-management skills include appropriate self-monitoring, the ability to organize and analyze your own data, accurate carb counting, dietary discipline, and the capacity to self-adjust insulin doses.

  •Attitude traits that contribute to success in diabetes self-care include determination, persistence, discipline, acceptance, and the ability to problem solve.

  CHAPTER

  5

  The Basal/Bolus Approach

  So you’ve got all your key components in place. Your home is littered with used test strips. Your carb-counting skills rival those of the diabetes gods. You’re even keeping written records for the first time in your life. Now all you need is the right insulin program to make it all pay off.

  If you’re going to think like a pancreas, your insulin program should include the two Bs: “basal” or “background” insulin, along with “boluses” or “bunches” of insulin at mealtimes.

  Basal Insulin

  The liver is a fascinating organ. It does about a hundred different things, but one of its main functions is to store glucose (in a dense, compact form called “glycogen”) and secrete it steadily into the bloodstream in order to provide your body’s vital organs and tissues with a constant source of fuel. This is what keeps your heart beating, brain thinking, lungs breathing, and digestive system, uh, digesting pretty much all the time.

  In order to transfer the liver’s steady supply of glucose into the body’s cells, the pancreas normally secretes a small amount of insulin into the bloodstream every couple minutes. This is called basal insulin. Not only does basal insulin ensure a steady energy source for the body’s cells, but it also keeps the liver from dumping out too much glucose all at once. Too little basal insulin—or a complete lack of insulin—would result in a sharp rise in blood sugar levels.

  So you might say that basal insulin and the liver are in equilibrium with each other. The basal insulin should match the liver’s secretion of glucose throughout the day and night. In the absence of food, exercise, and rapid-acting/mealtime insulin, the basal insulin should hold the blood sugar level nice and steady.

  Each person’s basal insulin requirement is unique. Typically, basal insulin needs are highest during the night and early morning, and they are lowest in the middle of the day. This is due to the production of blood sugar–raising hormones during the night as well as enhanced sensitivity to insulin that comes with daytime physical activity. Figure 5-1 below illustrates how various hormones play a role in the liver’s glucose output. Two hormones in particular—cortisol and growth hormone—cause the liver’s natural ebb and flow in glucose secretion.

  Figure 5-1. The influence of hormones on the liver’s glucose secretion

  Figure 5-2 shows typical basal insulin requirements for people with insulin-dependent diabetes. The chart is based on data from several hundred insulin pump users whose basal insulin levels were carefully adjusted and fine-tuned.

  Although no significant differences were found in the basal insulin requirements for men and women, age does play a significant role. During a person’s growth years (prior to age twenty-one) basal insulin needs tend to be relatively high throughout the night, drop through the morning hours, and gradually increase from noon to midnight. Most adults (age twenty-one-plus) exhibit an abrupt increase in basal insulin requirements during the early morning hours, followed by a drop-off until noontime, a low/flat level in the afternoon, and a gradual increase in the evening. This peak in basal insulin during the early morning hours is commonly referred to as a dawn phenomenon.

  Figure 5-2. Typical basal insulin levels by age group

  The pattern of basal insulin requirements reflects the amount and timing of cortisol and growth hormone secretion within each age category. The youngest group (younger than ten) requires approximately 40 percent less basal insulin than those eleven to twenty, but the twenty-four-hour pattern of peaks and valleys is remarkably similar. Likewise, the oldest group (over sixty) requires approximately 33 percent less basal insulin than those in the twenty-one to sixty age group, but they have a similar twenty-four-hour pattern.

  Basal insulin patterns are dictated mainly by when the body produces hormones that influence the liver’s secretion of glucose.

  Basal insulin can be supplied in a variety of ways. Intermediate-acting insulin (NPH) taken once daily will usually provide background insulin around the clock, albeit at much higher levels four to eight hours after injection and at much lower levels after sixteen to twenty-four hours. Long-acting basal insulins (glargine and detemir) offer relatively peakless insulin levels for approximately twenty-four hours. Insulin pumps deliver rapid-acting insulin in small pulses throughout the day and night. With a pump the basal insulin level can be adjusted and fine-tuned to match your body’s ebb and flow in basal insulin needs. Combining various forms of long-acting insulin to simulate the body’s normal basal insulin secretion is also possible.

  The following figures illustrate the action profiles of various types of basal insulin programs.

  Figure 5-3. Basal insulin supplied by NPH at bedtime

  The main advantage of this program is the peak that occurs during the predawn hours. The disadvantages include the unpredictability of the peak (due to NPH’s varied rate of absorption from day to day), the potential for low glucose in the early morning (due to the significant peak during the night), and the likelihood that late afternoon/evening blood sugar will rise as the NPH tapers off.

  The advantages of this program are the peak in basal insulin during the night and the possibility of using the morning NPH peak to cover the carbs eaten at lunchtime. The drawbacks are the same as those in Figure 5-3 above, plus the major issue of having to conform to a rigid meal/snack schedule during the day due to the peak of the morning NPH insulin. As the graphic clearly shows, this type of basal insulin program does a poor job of matching the body’s needs. It rarely produces stable glucose levels, particularly during the daytime.

  Figure 5-4. Basal insulin supplied by NPH in the morning and evening

  Unfortunately, those who use premixed insulin twice daily are, essentially, utilizing th
is approach for their basal program. Each injection of premixed insulin contains anywhere from 50 to 75 percent NPH insulin, with the remainder being either regular or rapid-acting insulin.

  Glargine (Lantus) is usually taken once daily, but sometimes it is taken twice, particularly when low doses are being used. Detemir (Levemir) is usually taken twice daily, but occasionally it can be taken once a day. When basal insulin is injected twice daily, splitting the doses evenly and taking them approximately twelve hours apart is reasonable. Taking more in the evening and less in the morning does not usually produce a desired peak at any particular time. When taken once daily, it is usually best to take the injection in the morning on a consistent twenty-fourhour cycle. Research has shown that the morning injection has the least potential to cause an undesired blood sugar rise when the insulin is tapering off at around twenty to twenty-four hours.

  Figure 5-5. Basal insulin supplied by glargine (Lantus) or detemir (Levemir)

  The main advantage of using glargine or detemir is the relatively unwavering flow of insulin (a very slight peak may occur six to ten hours after injection of detemir) and consistent absorption pattern. The disadvantages include the potential for a gradual blood sugar rise during the night (due to the lack of a predawn peak) and around the time of the injection when the insulin is taken once daily, as the basal insulin may wear off a few hours early and take a few hours to kick in. There is also potential for a gradual blood sugar drop in the afternoon as the basal insulin level may exceed the liver’s production of glucose.

  Figure 5-6. Basal insulin supplied by glargine or detemir plus evening NPH

  In order to overcome some of the potential problems created by using only basal or NPH insulin to meet the body’s basal needs, you can combine the two. When NPH is added at nighttime, glargine or detemir can be taken once daily at a lower dose than if used without NPH. This minimizes the risk of having glucose levels drop between meals during the day. By adding a modest evening or bedtime dose of NPH, you can achieve a nighttime/early-morning peak. This program offers the unique advantage of allowing day-to-day adjustment of the overnight basal insulin level by making minute changes to the NPH dose without affecting the basal insulin level the following day.

  The disadvantages include the need for at least two separate injections and the filling of multiple prescriptions. There is also potential for mixing up doses or taking the wrong insulin at the wrong time because several different types of insulin are being utilized simultaneously.

  Figure 5-7. Basal insulin supplied by insulin pump therapy

  Pump therapy offers the greatest degree of maneuverability in terms of matching basal insulin to the body’s needs. Because the pump uses small pulses of rapid-acting insulin to deliver basal insulin, variations in peak or action time are not an issue. Changes can be made to the basal insulin delivery on the hour or half-hour, so you can easily build peaks and valleys into the program. Pumps also permit temporary changes to basal insulin levels in order to accommodate shortterm changes in basal insulin needs (for situations such as illness, high/low activity levels, and stress).

  Perhaps the greatest drawback to delivering basal insulin with a pump is the risk of ketoacidosis. Any mechanical problem resulting in a lack of basal insulin delivery can result in a severe insulin deficiency in just a few hours. Without any insulin in the bloodstream, the body’s cells begin burning large amounts of fat (instead of sugar) for energy. This results in the production of acidic ketone molecules—a natural waste product of fat metabolism. This rarely occurs when taking injections of long-acting insulin because there is almost always some insulin working as long as injections are not missed.

  Bolus Insulin

  Insulin peaks are necessary because of the rapid blood sugar rise that occurs after eating carbohydrates (sugars and starches). Carbohydrates usually take about ten to twenty minutes to begin raising the blood sugar level, with a high point occurring thirty to ninety minutes following a meal.

  Option A: Rapid Insulin

  Rapid-acting insulin analogs such as aspart (Novolog/NovoRapid), glulisine (Apidra), and lispro (Humalog) peak sharply about sixty to ninety minutes after injection. You can use these insulins effectively to cover meals and minimize postmeal blood sugar spikes when taken at the right times (usually prior to eating). Rapid insulin is particularly effective when consuming rapid-digesting sugars and starches, such as bread, cereal, potato, rice, pastries, and sugary candies. It also permits the quickest fix for high blood sugar levels.

  Option B: Regular Insulin

  Regular insulin, by contrast, usually takes thirty minutes to begin working and peaks two to three hours after injection. Due to its relatively slow/inconsistent peak and long duration of action (up to six hours), regular is not usually the preferred insulin to use at mealtimes. Postmeal glucose levels tend to spike up very high for the first couple of hours and then plummet over the next several hours. Taking regular insulin thirty to sixty minutes before a meal mitigates this problem, but this is rarely practical. However, regular insulin can still play a role at mealtimes, particularly when slow-digesting foods are being consumed (we’ll discuss this later in the section on postmeal control) or if you have a form of neuropathy called gastroparesis, which causes abnormally slow digestion.

  Option C: NPH Insulin

  In some cases intermediate-acting insulin (NPH) is used to cover a meal or snack that will be consumed four to six hours later. For example, NPH taken at breakfast can be used to cover the carbohydrates eaten at lunch. This may be the only available option for someone who is dependent on a caregiver to administer insulin and the caregiver is not available at lunchtime, such as a young child attending a school with limited nursing resources. However, because of its broad and inconsistent peak, NPH taken in the morning has a tendency to cause the blood sugar to drop before lunch, and it allows for a sharp rise after lunch.

  Figure 5-8 below compares how various insulins cover the blood sugar rise that occurs after carbohydrate-containing meals and snacks. As you can see, the insulin analogs (Humalog and Novolog) provide the closest match.

  Figure 5-8. Bolus insulin options

  Putting Them Together

  Selecting the best insulin program to meet your needs depends on a number of factors. If you have type 2 diabetes, LADA, or are in the honeymoon phase of type 1 diabetes, your pancreas may produce sufficient amounts of insulin to meet either your basal or bolus needs, but usually not both. (A lab test called a C-peptide can be performed to see how much insulin your pancreas produces on its own.)

  If you still produce some of your own insulin, you can determine your general insulin requirements by doing the following:

  •Check your blood sugar level at bedtime, have no snack, and then test first thing in the morning. If your blood sugar rises more than 30 mg/dl (1.7 mmol/l) while you sleep, your pancreas is not making enough insulin to cover your basal needs; you will require supplementary basal insulin. Glargine or detemir are excellent choices because of their steady action and relatively low risk for causing hypoglycemia.

  •Check your blood sugar before and again sixty to ninety minutes after eating a meal. If your blood sugar was normal (below 120 mg/dl or 6.8 mmol/l) before eating but rises above 180 mg/dl (10 mmol/l) after eating, you will probably need bolus insulin at mealtimes. In most cases, rapid-acting insulin analogs provide the best mealtime coverage.

  •If your blood sugar is usually over 200 mg/dl (11 mmol/l), distinguishing between basal and bolus insulin needs may be difficult. Not to worry: A combination of both should do the trick.

  If you have type 1 diabetes or have type 2 and are in need of an aggressive insulin regime, utilizing a program that combines both basal and bolus insulin is best.

  To select the basal/bolus insulin program that best meets your needs, the Consumer Reports approach can be very helpful. I appreciate the way Consumer Reports provides objective, side-by-side comparisons of the various features of competing products. Recognizing that
different features are important to different people, this approach makes choosing the products and services that will best meet your individual needs easy.

  Here, then, is my “Consumer’s Guide” to the most commonly used and recommended basal/bolus insulin programs:

  Table 5-1. Gary’s non-copyright-infringing comparison of basal/bolus insulin programs

  Option 1: (Pre)mixed twice daily

  Prebreakfast: NPH and rapid (in premixed formulation or combined manually)

  Predinner: NPH and rapid (in premixed formulation or combined manually)

  Figure 5-9. The action profile of NPH and rapid insulin taken twice daily.

  This was a common insulin program back in the 1970s and ’80s (with regular insulin instead of a rapid-acting analog). It can be delivered using premixed insulin (70/30 or 75/25) in pen or vial/syringe form, or the user can combine it in a syringe manually. The premixed formulations have a major shortcoming in that you cannot change the proportion of intermediate to rapid insulin. If you need more rapid insulin, you must also take more intermediate (NPH) insulin, and vice versa. With the morning NPH insulin peaking in the afternoon, you must consume meals and snacks at specific times and in specific amounts. Changes to your usual schedule can lead to high and low glucose levels. Exercise during the day can also produce lows with this type of insulin schedule unless you consume extra carbohydrates. The evening NPH insulin peaks around midnight and dissipates as dawn approaches, predisposing most users to low blood sugar in the middle of the night and highs at wake-up.