Comparison of short-term diet and exercise on insulin action in individuals with abnormal glucose tolerance

The effects of a 10-day low-calorie diet (LCD; n = 8) or exercise training (ET; n = 8) on insulin secretion and action were compared in obese men (n = 9) and women (n = 7), aged 53 +/- 1 yr, with abnormal glucose tolerance by using a hyperglycemic clamp with superimposed arginine infusion and a high -fat drink. Body mass (LCD, 115 +/- 5 vs. 110 +/- 5 kg; ET, 111 +/- 7 vs. 1 09 +/- 7 kg; P < 0.01) and fasting plasma glucose (LCD, 115 +/- 10 vs. 99 /- 4 mg/dl; ET, 112 +/- 4 vs. 101 +/- 5 mg/dl, P < 0.01) and insulin (LCD, 23.9 +/- 5.6 vs. 15.2 +/- 3.9 mu U/ml; ET, 17.6 +/- 1.9 vs. 13.9 +/- 2.4 mu U/ml; P < 0.05) decreased in both groups. There was a 40% reduction in pla sma insulin during hyperglycemia (0-45 min) after LCD (peak: 118 +/- 18 vs. 71 +/- 14 mu U/ml; P < 0.05) and ET (69 +/- 14 vs. 41 +/- 7 mu U/ml; P < 0 .05) and trends for reductions during arginine infusion and a high-fat drin k. The 56% increase in glucose uptake after ET (4.95 +/- 0.90 vs. 7.74 +/- 0.82 mg.min(-1).kg fat-free mass(-1); P < 0.01) was significantly (P < 0.01 ) greater than the 19% increase (5.72 +/- 1.12 vs. 6.80 +/- 0.94 mg.min(-1) .kg fat-free mass(-1); P = not significant) that occurred after LCD. The ma rked increase in glucose disposal after ET, despite lower insulin levels, s uggests that short-term exercise is more effective than diet in enhancing i nsulin action in individuals with abnormal glucose tolerance.