GLYCEMIC RESPONSES TO EXERCISE IN IDDM AFTER SIMPLE AND COMPLEX CARBOHYDRATE SUPPLEMENTATION

OBJECTIVE - Subjects with IDDM should take carbohydrate before exercis e to avoid hypoglycemia. However, there is little information on the g lycemic effect of recommended supplementation. This study is aimed to determine the glycemic effects of oral glucose or bread (30 g carbohyd rate) before 45 min of moderate exercise. RESEARCH DESIGN AND METHODS - Nine subjects with uncomplicated IDDM did 45 min of bicycle ergomete r exercise at 60% Vo(2max) in the morning before insulin injection on three occasions: 1) with no carbohydrate supplement, 2) with 30 g gluc ose in water at -5 min, and 3) with 30 g carbohydrate as white bread n ith water at -20 min. The glycemic responses were determined. The glyc emic responses to glucose and bread were also determined without exerc ise in six subjects.RESULTS - Without carbohydrate, exercise caused a small fall(-1.2 +/- 0.6 mmol/l, mean +/- SE) in plasma glucose (PG). W ith either glucose or bread, PG rose (the change in plasma glucose rel ative to basal [Delta PG] = 5.1 +/- 0.8 and 2.6 +/- 0.8, respectively) . The rise was greater (P < 0.01) without exercise (Delta PG = 6.9 +/- 0.7 and 4.5 +/- 0.7, respectively). During exercise, glucose increase d PG levels more than bread increased glucose levels (P < 0.05). CONCL USIONS - Before morning insulin injection, the fall in PG during moder ate exercise in IDDM subjects is generally small or absent. The glycem ic effects or complex carbohydrate are slightly less than glucose befo re exercise. Under these circumstances, the usually recommended amount of carbohydrate tends to cause an unwanted elevation of PG; thus, IDD M subjects should anticipate reducing or even omitting carbohydrate su pplementation after monitoring their individual glycemic response.