Background: Although androgen deficiency in men has been linked with obesity and the metabolic syndrome, whether it predisposes to, or is a consequence of, type 2 diabetes mellitus (T2DM) is still unclear.
Objective: To determine the relationship between plasma androgen levels, obesity, metabolic status and T2DM in men of 70 years or older.
Design and methods: A sample of 195 men from the Australian Longitudinal Study of Ageing with a mean age of 76.2 +/- 0.3 years were followed up for 8 years. Total testosterone (TT), fasting plasma glucose (FPG), urate, serum creatinine, total cholesterol (TC), HDL cholesterol (HDL-C), LDL cholesterol (LDL-C), triglycerides (TG), blood pressure (BP), body mass index (BMI), waist circumference (WC) and diabetic status were assessed at baseline. Self-reported diabetic status was obtained after 8 years. Metabolic syndrome was diagnosed based on the Third National Cholesterol Education Program Adult Treatment Panel clinical criteria.
Results: TT levels were lower in diabetic men compared with non-diabetic men (12.1 +/- 0.7 vs. 14.2 +/- 0.4 nmol/l, p = 0.026). TT levels in healthy, non-diabetic men over 80 years of age were lower (11.9 +/- 0.8 vs. 15.0 +/- 0.5 nmol/l, p = 0.002) than TT levels in those aged 70-79 years, inversely related to BMI (r = -0.26, p = 0.001), WC (r = -0.30, p < 0.001) and TG (r = -0.22, p = 0.005) and positively related to LDL-C (r = 0.25, p = 0.002). Men with the metabolic syndrome had significantly lower levels of TT and HDL-C, and higher values of BP, FPG, TG, BMI and WC, compared with those without. However, no significant difference in plasma TT levels was noted between men with incident T2Dm and healthy men. Stepwise linear regression analysis revealed that only LDL-C and WC related significantly to the variance of TT. Multiple logistic regression revealed FPG to be the only independent predictor of incident diabetes (odds ratio = 60.2, p = 0.003).
Conclusions: Testosterone levels continue to decline even in healthy men over the age of 80 years. Although TT levels were inversely related to visceral obesity and several components of the metabolic syndrome, our data do not support a predictive or causative role for decreasing TT levels in the development of incident T2Dm. Androgen deficiency is consequent upon, rather than a cause of, poor metabolic status.