ORAL GLUCOSE-INGESTION INCREASES ENDURANCE CAPACITY IN NORMAL AND DIABETIC (TYPE-I) HUMANS

The effects of an oral glucose administration (1 g/kg) 30 min before e xercise on endurance capacity and metabolic responses were studied in 21 type I diabetic patients [insulin-dependent diabetes mellitus (IDDM )] and 23 normal controls (Con). Cycle ergometer exercise (55-60% of m aximal O-2 uptake) was performed until exhaustion. Glucose administrat ion significantly increased endurance capacity in Con (112 +/- 7 vs. 1 25 +/- 6 min, P < 0.05) but only in IDDM patients whose blood glucose decreased during exercise (70.8 +/- 8.2 vs. 82.8 +/- 9.4 min, P < 0.05 ). Hyperglycemia was normalized at 15 min of exercise in Con (7.4 +/- 0.2 vs. 4.8 +/- 0.2 mM) but not in IDDM patients (12.4 +/- 0.7 vs. 15. 6 +/- 0.9 mM). In Con, insulin and C-peptide levels were normalized du ring exercise. Glucose administration decreased growth hormone levels in both groups. In conclusion, oral glucose ingestion 30 min before ex ercise increases endurance capacity in Con and in some IDDM patients. In IDDM patients, in contrast with Con, exercise to exhaustion attenua tes hyperglycemia but does not bring blood glucose levels to preglucos e levels.