Glucose Tolerance in Women: The Effects of Age, Body Composition, and Sex Hormones

To determine the separate and interactive effects of age, phase of the menstrual cycle, menopausal hormone status, body fat mass, and regional fat distribution on glucose tolerance in healthy women. Retrospective study. The Baltimore Longitudinal Study of Aging. Two hundred sixty healthy women aged 22–89 years. Plasma levels of estradiol and progesterone, body mass index (BMI), waist‐to‐hip ratio (WHR), and plasma glucose values in the fasting state (FPG) as well as 120 minutes after 40 gm/m² of oral glucose (G₁₂₀) were measured for each participant. We found a progressive decline in oral glucose tolerance of 0.4 mm (6.7 mg/dL)/decade at G₁₂₀) in women from early to late adult years, with no relationship to phase of the menstrual cycle and no abrupt change associated with the menopause. Multiple regression analysis revealed significant, independent effects of BMI and WHR on FPG and G₁₂₀. The influence of age (P < 0.01) on G₁₂₀ was stronger than that of the BMI or WHR (P < 0.05). There was no significant relationship between the levels of endogenous sex hormones and glucose tolerance after adjustments for age, BMI, and WHR. However, women taking oral contraceptives, but not those receiving postmenopausal replacement therapy, did exhibit mildly elevated G₁₂₀ values. Age per se, and to a lesser extent BMI and WHR, but not levels of endogenous sex steroids, contribute to the physiological decline in glucose tolerance in older women.