Physical exercise is associated with a fall in serum
insulin levels, whereas sulphonylurea administration increases
insulin release. To date, the opposing effects of exercise and sulphonylurea administration have not been systematically studied in Type 2 diabetic patients, who are not infrequently treated with sulphonylureas. In this study nine patients with
Type 2 diabetes mellitus were subjected to four treatments in random order on separate days: (A) endurance exercise after the administration of 3.5 mg
glibenclamide; (B) as A but given only 1.75 mg
glibenclamide; (C) as A but with placebo; (D) rest and administration of 1.75 mg
glibenclamide. Exercise and placebo resulted in only a small decrease in glycaemia. Rest and administration of 1.75 mg
glibenclamide led to a moderate but steady fall in
blood glucose concentrations. If
glibenclamide administration and exercise were combined,
blood glucose concentrations declined more markedly. Serum
insulin concentrations showed a physiological decrease during exercise and placebo administration. If patients rested after administration of
glibenclamide serum
insulin levels rose and remained elevated. When exercise and
glibenclamide were combined the rise in serum
insulin levels was blunted and
insulin levels fell once exercise was begun. Thus, exercise attenuates the
glibenclamide induced increase in serum
insulin in moderately hyperglycaemic Type 2 diabetic patients. Nevertheless, exercise has a substantial hypoglycaemic effect in
glibenclamide treated Type 2 diabetic patients.