My five year old son (diagnosed at age three) recently started participating in little league baseball. We check his blood glucose right before he starts practice and give him a snack if necessary. What is the best food (in terms of glycemic index) for a young child involved in physical activity for an hour and a half?

There is no one “best food” answer to this question. The choice of carbohydrate (relative to the glycemic index) prior to activity should depend on a number of variables, including the type and intensity of the activity; the blood sugar levels before and during exercise, the relationship to insulin dose and peak time, and the timing of snack prior to exercise.

In general, sports such as baseball and softball usually require only short bursts of movement and are therefore more “anaerobic” in nature. You may not observe a dramatic change in blood sugar as a result. The total energy expenditure will also differ depending on the field position played. A pitcher or catcher, for example, is a much more active position than an outfielder, and this continuous activity will generally produce a greater decrease in blood sugar. Team practice, where there is more continuous activity than there might be during game play, may require greater adjustments in insulin or food intake. All of these factors must be considered in this decision. So too should your child’s snack preference.

High glycemic index carbohydrate choices include certain sports drinks, most juices, regular sodas, glucose tabs or gels, and many hard candies. These are generally recommended to treat a low blood sugar, or to sustain blood sugar levels during longer duration aerobic exercise. Medium glycemic index foods include bagels, breads, crackers, bananas, grapes, and raisins. Adding a fat or protein source (such as peanut butter or cheese) to a carbohydrate slows the rate of absorption, thereby lowering the glycemic index. Any of these may be good choices as snacks prior to exercise. A dietitian may have more specific and individualized recommendations for your son.

Continue patterning blood sugar response to activity by testing glucose levels before and after exercise. This will assist you in predicting the blood sugar response to exercise and in making appropriate choices regarding carbohydrate and insulin adjustments.

DMW