Updated August 04, 2006

Strike the Spike
Controlling After-Meal Blood Glucose Highs

by Gary Scheiner, M.S., C.D.E.

Think lower GI. The glycemic index of a food refers to the speed with which the food raises blood glucose level. While all carbohydrates (except for fiber) convert into glucose eventually, some do so much faster than others.

Many starchy foods, including many types of bread, cereals, potatoes, and rice have a high glycemic index; they digest easily and convert into glucose quickly. Some starchy foods, including pasta, beans, and peas, have a lower glycemic index because the starches contained in them do not digest as easily. Similarly, some sweet foods have a high glycemic index while others do not. Table sugar (sucrose), for example, has a moderate glycemic index. Foods that contain fiber or fat tend to have lower glycemic index values than foods that do not. Foods in solid form tend to have a lower GI than similar foods in liquid or “sauce” form, and cold foods tend to digest more slowly than hot foods.

A number of books contain extensive information about the glycemic index, including Dr. Jennie Brand-Miller’s Glucose Revolution series, which is readily available in bookstores. For a list of the glycemic index values of many common foods, see "Glycemic Index of Common Foods." (Higher numbers mean faster conversion to glucose.) Substituting foods with a lower glycemic index for foods with a higher glycemic index in your diet will help to reduce your after-meal blood glucose spikes.

Medicate wisely. Whether you take insulin or oral medicines to control your blood glucose levels, the right program can make or break your ability to control those after-meal spikes. In general, insulin and medicines that work slowly over a prolonged period do a poorer job of controlling after-meal spikes than those that work quickly and for a short period.

For insulin to control after-meal spikes, the insulin’s “peak” action must match the peak blood glucose level after eating. If you take a morning injection of NPH to “cover” the food you eat in the middle of the day, your postprandial blood glucose is likely to be very high after lunch and after any late-morning or afternoon snacks. That’s because the peak for these insulins is less pronounced than that of the rapid-acting insulins and it is spread over several hours. To remedy this, consider taking a dose of a rapid-acting insulin analog such as lispro (brand name Humalog) or aspart (NovoLog) before each meal and snack, with an intermediate insulin at nighttime only.

Even Regular insulin, with a peak taking place 2–3 hours after injection, rarely works as well at controlling after-meal blood glucose levels as does lispro or aspart, both of which peak about an hour after injection.

Your choice of oral medicine can also affect your after-meal control. Sulfonylureas (glyburide, glipizide, glimepiride), which are generally taken once or twice a day, stimulate the pancreas to secrete a little extra insulin throughout the day, without regard to meal timing. Because these medicines fail to concentrate the insulin secretion at times when it is needed most, after-meal blood glucose levels can run very high. However, the drugs repaglinide and nateglinide, which also stimulate the pancreas to secrete more insulin, are much faster- and shorter-acting. When taken at mealtimes, these drugs stimulate the pancreas to secrete extra insulin for a concentrated period of time, thus producing better after-meal control.

Another class of diabetes medicines called alpha-glucosidase inhibitors improve after-meal control by partially blocking the transport of some carbohydrates across the intestines and into the bloodstream. However, these drugs can sometimes cause temporary gas, bloating, and gastrointestinal upset. You might recall that physical activity after meals will also slow the movement of carbohydrates into the bloodstream, but without the side effects!

Gary Scheiner is a Certified Diabetes Educator with a private practice, Integrated Diabetes Services, near Philadelphia. He is the author of the book Think Like a Pancreas, and he offers diabetes education and management consultations via phone, fax, and Internet to people throughout the world. Submit questions and inquiries to garyscheiner@prodigy.net, or call (877) 735-3648.

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