Specific Relation Between Abdominal Obesity and Early-Phase Hyperglycemia Is Modulated by Hepatic Insulin Resistance in Healthy Older Women

OBJECTIVE To describe the impact of abdominal obesity and hepatic insulin resistance on phase-specific glycemic responses in older women. RESEARCH DESIGN AND METHODS We studied 23 healthy older women (60-88 years old). Abdominal obesity was defined by an abdominal circumference > or =95 cm. Plasma glucose and insulin were measured in response to a 3-h oral glucose tolerance test. Insulin suppression of hepatic glucose production was determined using in vivo clamp techniques. RESULTS Despite identical prevailing insulin concentrations, glucose excursions 30 min postchallenge (but not later) were greater in women with abdominal obesity than in those without (162 +/- 19 vs. 132 +/- 16 mg/dl; P < 0.01). There was a strong correlation between hepatic glucose production suppression under low-dose insulin infusion and early-phase glucose excursions from the oral glucose tolerance test (r = -0.83; P < 0.001) in women with abdominal obesity, but not in women without (r = 0.44; P < 0.11). CONCLUSIONS Abdominal obesity relates specifically to early-phase hyperglycemia via hepatic insulin resistance, even in healthy older women.