Updated August 04, 2006

Strike the Spike
Controlling After-Meal Blood Glucose Highs

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

When interpreting your results, take your premeal readings into account since you are interested in not just your after-meal reading but also in how much your blood glucose level increased because of your food intake. For example, a postmeal blood glucose reading of 240 mg/dl following a premeal reading of 210 mg/dl shows just a 30-point rise, whereas a 240 mg/dl following a 110 mg/dl shows a 130-point rise. Having a mildly low blood glucose value (around 65 mg/dl, for example) before a meal can result in a temporary “rebound” to a higher-than-usual level after the meal and may not reflect a true postprandial spike.

Another option for analyzing after-meal blood glucose levels is the GlucoWatch Biographer from Cygnus Corporation. The GlucoWatch takes readings every 10 minutes by measuring the concentration of glucose in the interstitial fluid just below the skin. The data can be reviewed manually or transferred to a computer for analysis. However, one of the problems with using the GlucoWatch is its tendency to “skip” readings during periods of rapid blood glucose rise or fall, as usually occurs soon after eating.

A more detailed analysis of after-meal blood glucose can be obtained through use of the Continuous Glucose Monitoring System (CGMS) from Medtronic MiniMed. The CGMS can be worn for up to three days and measures glucose levels in interstitial fluid by way of a tiny sensor inserted just below the skin. It does not provide immediate data. Instead, the information is transferred to a computer after the sensor is disconnected from the skin. The software provides statistics and graphic printouts that allow you and your health-care team to see exactly how much your blood glucose levels are rising after meals and snacks. (See sample printouts in "How Bolus Timing Affects After-Meal Spikes").

Spike control
Reducing after-meal spikes does not always mean taking more insulin or oral medicine at mealtimes. In fact, if your premeal readings are already close to normal, increasing your dose of insulin or oral medicine would result in low blood glucose before the next meal. Remember, the idea is to reduce the between-meal peak, but not necessarily lower the blood glucose level before the next meal.

To accomplish this feat, a number of strategies can be used, including the following:

Get moving. Physical activity after eating has a multitude of benefits. If insulin was taken with the meal or snack, the enhanced blood flow to the skin surface caused by physical activity is likely to make the insulin get absorbed quicker so that it can act quicker. This means that the insulin will do a better job of keeping the blood glucose from rising too high right after eating. In addition, muscle activity diverts blood flow away from the intestines, resulting in slower absorption of glucose and other simple sugars into the bloodstream. The sugars that do enter the bloodstream are likely to be “consumed” by the working muscles.

How much activity is required to experience these benefits? Not much. Ten or 15 minutes (or more) of mild activity will get the job done. The key is to avoid sitting for extended periods after eating. Instead of reading, watching TV, or working on the computer, go for a walk, shoot some hoops, or throw a few darts. In the course of your usual day, try to schedule your active tasks (housework, yardwork, chores, errands, walking pets) for after meals. Make an attempt to schedule your exercise sessions for after meals to take advantage of their blood-glucose-lowering effect. (Individuals with heart disease or other circulatory complications should consult their physician before attempting to exercise after eating.) When you go out for a meal, resist the urge to sit and talk for hours or head straight for a movie. Instead, get up and go out dancing, bowling, or skating.

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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