DECREASE IN BLOOD GLUCOSE IN ADOLESCENTS WITH IDDM AS A FUNCTION OF INITIAL BLOOD GLUCOSE, WITH AND WITHOUT CHO INGESTION 235

Abstract

Prolonged exercise causes blood glucose (BG) to decrease in well insulinized individuals with insulin-dependent diabetes mellitus (IDDM). In an attempt to determine the influence of pre-exercise BG (BGpre), and carbohydrate (CHO) ingestion on the rate of drop in BG, 8 adolescent males with IDDM participated in 2 experimental protocols (A & B) spaced 1-4 weeks apart. In protocol A, subjects drank water during 60 min. of moderate intensity cycle ergometry exercise, 75min after insulin injection and a standardized breakfast. Total CHO utilization was determined based on respiratory exchange ratio and O2 uptake. In protocol B, subjects ingested a CHO beverage (13C enriched, 8% glucose solution, 18mmol-1 NaCl) equal to the amount of CHO utilized in protocol A, during an identical exercise challenge. Percent exogenous CHO (CHOexo) oxidation was calculated in protocol B using the expired13 CO2/12CO2 ratio. Total CHO utilization was 85±25g (mean±SD) in protocol A and CHOexo oxidation was 13±4% in protocol B. The rate of drop in BG was higher in protocol A than in B (9.1±3.8 vs 3.6±3.3 mmol-1·65min-1, respectively) The rate of drop was correlated to BGpre in protocol A (r=.86, p<0.01) and marginally so in protocol B (r=.64, p=0.08). Percent CHOexo oxidation was not correlated with BGpre (r=.08). These data suggest that pre-exercise blood glucose influences the rate of drop in blood glucose but does not influence CHOexo oxidation.