Sex-related differences in peripheral glucose metabolism in normal subjects

The metabolic response of muscle tissue to glucose ingestion was studied in 10 normal men (M) and women (F) by using the forearm balance technique and indirect calorimetry simultaneously. During the 3 hours after a 75 g--oral glucose load, glucose uptake per unit muscle mass was significantly higher in women than in men, F = 187.3 +/- 26.9 vs M = 116.7 +/- 9.5 mg/100 g forearm muscle (P less than 0.05). A significant difference in muscle glucose fate was also observed since the amount of glucose utilized through a nonoxidative pathway was significantly higher in women, F = 84.5 +/- 2.6% (161.8 +/- 27.3 mg/100 g forearm muscle) vs M = 75.3 +/- 2.2% (87.2 +/- 8.6 mg/100 g forearm muscle) (P less than 0.05), whereas the amount of glucose oxidized in relation to glucose uptake was significantly higher in men, M = 24.7 +/- 2.2% (28.2 +/- 3.2 mg/100 g forearm muscle) vs F = 15.5 +/- 2.6% (27.8 +/- 5.4 mg/100 g forearm muscle) (P less than 0.05). No significant differences in insulin response to glucose ingestion were detected between groups. The women showed greater suppression of serum free fatty acids (FFA) levels in relation to basal levels than men. We conclude that: 1) after ingesting 75 g glucose, normal women showed greater glucose uptake per unit muscle mass than normal men, 2) for 3 hours after the ingestion of 75 g glucose, the predominant tendency toward utilizing glucose by a nonoxidative pathway is more marked in normal women than in normal men, and 3) the higher glucose uptake per unit muscle mass in the female group in the presence of an insulin response not significantly different from that of the male group suggests that muscle insulin sensitivity is greater in normal women.