Think Like a Pancreas

by Gary Scheiner

  Preventing Lows

  Minimizing the incidence of low blood sugar can go a long way toward protecting your personal safety and keeping blood sugar levels from bouncing around too much as a result of rebounds. Minimizing the incidence of lows is also the best way to ensure that you will experience early symptoms when your blood sugar is dropping and thus be able to treat the low before it becomes severe.

  Experiencing a couple of mild low blood sugars per week is usually acceptable. However, if they are occurring more often or if they are of a severe nature, try applying these strategies:

  Match Your Insulin to Your Needs

  The first step in preventing lows is the same as the first step in achieving tight control: Mimic the action of a healthy pancreas as closely as possible. Daytime doses of NPH in particular do not match the basal/bolus insulin secretion of the pancreas nearly as well as programs that utilize basal insulin. NPH insulin can peak at inconsistent and inappropriate times, thereby increasing the odds of low blood sugar. Switching to a true basal insulin (glargine, detemir, or an insulin pump) will greatly reduce your risk for hypoglycemia.

  Use Rapid-Acting Insulin

  Rapid-acting insulin analogs (Humalog, Novolog/NovoRapid, Apidra) tend to produce fewer low blood sugars than regular insulin does. Their rapid onset, consistent peak, and short duration of action match up well to the absorption of carbohydrates in most meals. Regular insulin peaks later and lasts significantly longer. It has a tendency to make blood sugars drop three to six hours after eating—long after the food has been digested and absorbed into the bloodstream.

  Dose Properly

  Accidental overdosing of insulin is a common cause of hypoglycemia. If you are on relatively low doses (less than 5 units per injection), look for syringes or pens that offer half-unit markings so that you can dose more precisely. You also have the option of diluting your insulin for more precise dosing, as I described in Chapter 4. If you have difficulty seeing your syringes, use an insulin pen or injection aid. (See Chapter 10.) If necessary, have someone else draw up your syringes. And pay attention to your math! A single incorrect calculation can send your blood sugar spiraling downward. If you accidentally take too much insulin, drink or eat enough carbs to offset the extra dose and then check your blood sugar hourly until the insulin wears off.

  Give Your Insulin Time to Work

  As discussed in Chapter 7, boluses of rapid-acting insulin do not stop working after just an hour or two; rather, they typically take three to five hours to finish working. When figuring the amount of correction insulin needed to bring a high blood sugar down to normal, taking the unused portion of your previous boluses into account is important. Likewise, figuring the amount of bolus insulin required to cover a meal should be based on the blood sugar three to four hours after the meal. If you set your doses so that your blood sugar is down to normal two hours after eating, you are likely to experience hypoglycemia within the next couple of hours.

  Time Your Boluses Properly

  Foods that have a low glycemic index value tend to take a while to raise the blood sugar level. Very large meals that contain a great deal of fat can also take a while to raise the blood sugar. Giving a bolus before or during these types of meals can cause low blood sugar soon after eating. Instead, plan to give your boluses after eating or, if using an insulin pump, program the bolus to be delivered over an extended period of time. These strategies are also helpful for preventing postmeal blood sugar drops when using Symlin (pramlintide), Byetta (exenatide), or Victoza (liraglutide).

  Set Appropriate Targets

  The lower your target blood sugar, the greater your chances for hypoglycemia—plain and simple. Target blood sugars of 80 or 90 (4.4–5.0) leave little margin for error. Even the slightest bit of extra exercise or a minor overestimate of carbohydrates will probably result in a low. A target of 100 (5.6) or more allows a bit more breathing room. Some people change their target BG from day to day based on their risk for lows. If you’re coming off a day when a low occurred, your BG was very erratic, or you exercised heavily, your risk for hypoglycemia is increased. Raising your target modestly can save you from lows.

  Also, make sure your correction formulas are set properly. A sensitivity factor that is set too low will cause overdosing for high readings and lead to hypoglycemia. As mentioned in Chapter 7, sensitivity factors are often higher at night than they are during the day. And don’t forget to reduce your mealtime boluses any time the blood sugar is below target.

  Time Meals and Snacks Appropriately

  When using any type of intermediate- or long-acting insulin, consuming your meals and snacks on a consistent schedule is imperative. A delay of as little as half an hour (when using daytime NPH) or an hour (when using glargine or detemir) can cause a significant drop in blood sugar. If you anticipate a meal delay, consume part of your usual meal in the form of a carbohydrate-containing snack.

  Discount Fiber Grams

  Don’t forget: Fiber is included in the “total carbohydrate” listings on food labels, but it does not raise blood sugar levels. Any time you are consuming a food item that contains fiber, subtract it from the total carbohydrate before calculating your meal bolus.

  Adjust for Exercise and Daily Activity

  Physical activity of almost any kind (from running laps to running a vacuum) will accelerate muscle cells’ uptake of glucose. In those without diabetes insulin secretion comes to a grinding halt and production of counter-regulatory hormones increases at the onset of exercise. This helps to maintain blood sugars within normal limits. For those who take insulin, however, adjustments must be made to prevent low blood sugar during and after exercise. For activity performed after a meal, you will probably need to reduce the meal bolus. Activity before or between meals will probably require an extra snack. Prolonged or very strenuous activity may require reductions in both basal and bolus insulin, along with periodic snacks. Following exhaustive forms of exercise, you should make adjustments to prevent a delayed blood sugar drop.

  Adjust for Alcohol

  In Chapter 8 we discussed how alcohol can cause a delayed drop in blood sugar by suppressing the liver’s secretion of glucose. After drinking be sure to either lower your basal insulin level for several hours or consume extra snacks to compensate.

  Check, Check, Check

  Very few of us are good at guessing our blood sugar levels with much precision, especially when the readings are not particularly high or low. Frequent blood sugar checks will allow you to catch many below-target readings before they turn into hypoglycemia. For instance, a bedtime reading of 82 (4.6) may seem innocuous, but even a slight drop during the night would result in a low blood sugar. Knowing that the reading is close to low allows you the opportunity to have a small snack, thus reducing the likelihood of hypoglycemia during the night.

  Use a Continuous Glucose Monitor

  CGMs allow us to prevent low blood sugar and catch them as early as possible.

  Continuous glucose monitors provide the user with low blood sugar alerts. The threshold for the alert can be set above the level at which you begin to notice symptoms so that you can catch your lows as early as possible. Some CGM systems also provide predictive alerts: If they anticipate that you will go low based on the current glucose level and direction the blood sugar is headed, it can alert you. Others provide rate of change alerts, which can let you know if your blood sugar is dropping very quickly—even if it is still in a normal range—so that you can decide whether you need a snack to prevent hypoglycemia.

  Overall, continuous glucose monitors are effective tools for reducing the incidence of low blood sugar and catching them as early as possible. Research has shown that the average length of low blood sugar episodes is cut in half when the low alerts are used. This is very important because the length of a low, and not necessarily the severity of the low, is what puts us at risk for seizures and loss of consciousness.

  Dealing with Postmeal Highs

  At the opposite e
nd of the spectrum from lows are high blood sugar levels. An almost unlimited number of factors can cause highs, but you can usually prevent (and always fix) them with additional insulin.

  One type of high that causes frustration for many people is the one that occurs soon after eating. We call this a “postmeal spike.” Postmeal spikes are temporary high blood sugars that occur approximately one to two hours after eating. It is normal for the blood sugar to rise a small amount after eating, even in people who do not have diabetes. However, if the spike is too high, it can affect your quality of life today and contribute to serious health problems down the road.

  The reason blood sugar spikes very high after eating for many people with diabetes is a simple matter of timing. In a person without diabetes, consumption of carbohydrate results in two important reactions: the immediate release of insulin into the bloodstream and the production of amylin. Insulin produced by the pancreas starts working almost immediately and finishes its job in a matter of minutes. Amylin keeps food from reaching the intestines too quickly (where the nutrients are absorbed into the bloodstream). As a result, the moment blood sugar starts to rise, insulin is there to sweep the extra sugar into the body’s cells. In most cases, the after-meal blood sugar rise is barely noticeable.

  The reason blood sugar spikes after a meal is that insulin is too slow to cover most of the food we eat.

  However, people with diabetes are like a baseball player with very slow reflexes. We’re in the batter’s box facing a pitcher who throws 98-mph fastballs; by the time we swing, the ball is already in the catcher’s mitt. Rapid-acting insulin that is injected (or infused by a pump) takes approximately fifteen minutes to start working, sixty to ninety minutes to peak, and three to five hours to finish working. And don’t forget about the amylin hormone effect. In people type 2 diabetes, amylin is produced in insufficient amounts. Those with type 1 diabetes produce none at all. As a result, food digests even faster than usual. This combination of slower insulin and faster food digestion can cause blood sugar to rise quite high soon after eating. This is followed by a sharp drop once the mealtime insulin finally kicks in.

  Why Are Spikes a Problem?

  Even though the spike is temporary, all of those spikes throughout the day can raise your HbA1c. Maintaining an A1c below 7 percent without paying attention to after-meal blood sugar levels is difficult. Scientists and doctors have studied the long-term effects of postmeal highs extensively. For those with type 1 diabetes, significant postmeal rises have been shown to produce earlier onset of kidney disease and accelerate the progression of existing eye problems (retinopathy). And postmeal hyperglycemia is an independent risk factor for cardiovascular problems for those with type-2 diabetes.

  But the problems are not limited to long-term complications. Any time blood sugars rise particularly high—even temporarily—our quality of life suffers. Energy decreases, brain function falters, physical/athletic abilities become diminished, and moods become altered. During pregnancy even mild rises in blood sugar after meals have been associated with excessive and unhealthy growth of the baby.

  Measurement and Goals

  The exact timing of blood sugar spikes can vary from person to person and meal to meal. However, on average the postmeal peak tends to occur about one hour and fifteen minutes after starting a meal. So checking your blood sugar (using a fingerstick) about an hour after finishing a meal should provide a good indication of how much of a spike is taking place. Continuous glucose monitors provide trend graphs that make seeing exactly what is happening after meals easy. See the example in Figure 9-3.

  Figure 9-3. CGM display showing postmeal peaks

  Another way to assess after-meal blood sugar control is through a blood test called “GlycoMark.” Just as an HbA1c measures average blood sugar for the past few months, GlycoMark measures the degree to which blood sugars are spiking over the past couple of weeks. Glyco- Mark measures the level of a specific type of sugar that becomes depleted whenever the kidneys are spilling sugar into the urine (typically when BG exceeds approximately 180mg/dl or 10 mmol/l). Ask your physician if this test is available to you.

  The American Diabetes Association recommends keeping blood sugar below 180 mg/dl (10 mmol/l) one to two hours after eating. The European Diabetes Policy Group recommends keeping it below 165 mg/dl at the peak, and the American Association of Clinical Endocrinologists and International Diabetes Federation suggest keeping it below 140 mg/dl after eating. However, no specific guidelines are provided for type 1 versus type 2 diabetes, insulin users versus noninsulin users, or children versus adults. (Not surprisingly, none of these groups suggest how to meet those goals either.)

  A summary of my recommendations for postmeal glucose is listed in Table 9-2.

  Table 9-2. Summary of after-meal blood sugar targets

  Group/age Postmeal goal

  Adults taking mealtime insulin <180 mg/dl (10 mmol/l)

  Adolescents with type 1 <200 mg/dl (11)

  School-age children with type 1 <225 mg/dl (12.5)

  Preschool/toddlers with type 1 <250 mg/dl (14)

  Women during pregnancy <140 mg/dl (8)

  Type 2s taking basal insulin only <160 mg/dl (9)

  Spike Control

  If your doctor’s only answer for controlling the after-meal spikes is “Just take more insulin,” think again. Increasing the amount of insulin does little to reduce the immediate postmeal spike, but it will almost surely make you go low before the next meal.

  To reduce the spike, you can use a number of strategies. Some involve medications, whereas others involve daily lifestyle patterns.

  1. Choose the right insulin (or medication)

  The right insulin or medication program can make or break your ability to control those after-meal spikes. In general, insulin and medications that work quickly and for a short period of time will work better than those that work slowly over a prolonged period of time.

  If you are still using regular insulin at mealtimes (or daytime NPH to cover your midday meal), switch to a rapid-acting insulin analog (Humalog, Novolog/NovoRapid, or Apidra). If you have type 2 diabetes and take a sulfonylureas (glyburide, glipizide, glimepiride), switch to a rapid (and shorter)-acting meglitinide (repaglinide, nateglinide). Another class of diabetes medications that can improve after-meal control by partially blocking the transport of sugars across the intestines and into the bloodstream is called “alpha-glucosidase inhibitors.” However, be aware that this class of medications can cause gastrointestinal upset, gas, and bloating.

  2. Back Up Your Bolus

  As I discussed in Chapter 7, the timing of your mealtime insulin can make a huge difference in your postmeal control. Boluses given too late to match the entry of sugars into the bloodstream can produce significant hyperglycemia soon after eating, whereas a properly timed bolus can result in excellent after-meal control. In general, giving your bolus fifteen to twenty minutes before eating should result in less of a spike than bolusing just before or during your meals.

  3. Use a Jet Injector

  Jet injectors are insulin injection devices that spray insulin through the skin at a high speed in a “mist” form. By spreading the insulin molecules over a wider area under the skin than syringes, pens, and pumps do, the insulin starts working faster, peaks earlier and stronger, and finishes working sooner.

  4. Bolus for the Basal

  In order to have more insulin working right after eating and less working several hours later, a pump user can run a temporary basal reduction for three hours just before eating and give a normal bolus equal to the basal insulin that would have been delivered. For example, if your basal rate in the morning is .7 units per hour, you could bolus an extra 2 units before breakfast and then set a temp basal of 10 percent (90 percent reduction) for the next three hours.

  5. Use an Incretin

  Three injectable hormones—Symlin (pramlintide) and Byetta (exenatide) have powerful effects on postmeal blood sugar. Both slow gastric emptying and keep car
bohydrates from raising the blood sugar too quickly after meals. They also blunt appetite and inhibit secretion of the blood sugar-raising hormone glucagon after meals. Of the two, Symlin (taken before eating) tends to produce the best aftermeal control.

  6. Think Lower GI

  As I discussed in Chapter 7, glycemic index (GI) refers to the speed with which food raises the blood sugar level. Although all carbohydrates (except for fiber) convert into blood sugar eventually, some carbs do so much faster than others do. As a general rule, switching to lower-GI foods will help reduce your after-meal blood sugar spikes. Table 9-3 shows some examples.

  Table 9-3. Substituting low-GI for high-GI foods

  Meal High-GI choices Lower-GI choices

  Breakfast typical cereal, bagel, toast, waffles, pancakes, corn muffins, juice, breakfast bars high-fiber cereal, oatmeal, yogurt, whole fruit, milk, bran muffin, granola