Effects of exercise intensity on insulin sensitivity in women with non-insulin-dependent diabetes mellitus

Exercise enhances insulin sensitivity in people with non-insulin-dependent diabetes mellitus (NIDDM), but the intensity of exercise necessary to optimize the effect is unknown. Eight women with NIDDM were studied on a metabolic ward in each of three conditions: 1) low-intensity exercise (LO) that consisted of treadmill walking at 50% of maximal O2 consumption on days 1 and 2, 2) high-intensity exercise (HI) that consisted of walking at 75% of maximal O2 consumption, and 3) no exercise (NX). The duration of exercise was adjusted so that energy expenditure was equal in both exercise conditions. On day 3, glucose, [6,6-2H]glucose, and insulin were infused at fixed rates for 3 h. Insulin sensitivity was determined both by steady-state plasma glucose concentration and rate of glucose disposal per unit plasma insulin. Steady-state plasma glucose concentration and rate of glucose disposal per unit plasma insulin were almost identical after LO or HI; values were significantly greater than after NX. Plasma glucose response to a test meal was the same among the three conditions, but plasma insulin response was lower for HI and LO compared with NX. We conclude that under these conditions LO is as effective as HI in enhancing insulin sensitivity in people with NIDDM.