Glucose clearance is delayed after hyperglycemia in healthy elderly men

Delayed glucose clearance after hyperglycemia may contribute to insulin resistance. Rates of glucose and insulin decay were measured after 3 h of sustained hyperglycemia (10 mmol/L) in 8 healthy older men (66 ± 2y) and were compared with those of 8 younger men (22 ± 1y). Fractional glucose clearance rates were calculated by regression analysis. Insulin decay was estimated from insulin levels through 30 min postinfusion. Abdominal adiposity was estimated from waist-to-hip ratios. Body weight and basal plasma glucose, insulin and C-peptide concentrations did not differ between groups. Fat mass, abdominal adiposity, fasting serum triglycerides and total cholesterol, although normal, were higher (P < 0.05) in the older group. The elderly group experienced lower glucose clearance rates (1.9 ± 0.2 vs. 2.9 ± 0.1%/min, P < 0.002) and higher plasma insulin after hyperglycemia (P < 0.03). Glucose and insulin decay correlated with glucose infusion rates (r = 0.88, P < 0.0002 and r = 0.51, P < 0.05). Delayed glucose clearance was associated with greater abdominal adiposity (r = -0.56, P < 0.03), higher serum triglycerides (r = -0.73, P < 0.003) and elevated serum cholesterol (r = -0.56, P < 0.04). In conclusion, modest increases in abdominal adiposity and circulating lipids are associated with abnormal glucose clearance in clinically healthy older men; this may be a precursor to the development of insulin resistance and related complications that arise from prolonged postprandial hyperglycemia.