The association between serum total testosterone and progression of hyperglycemia: a 15-year prospective cohort study

The association between low testosterone concentration and increased risk of hyperglycemia in men has been demonstrated in observational and interventional studies. However, considering a variety of confounding factors, limited population-based studies have so far been conducted. Also, no information is available regarding the effect of testosterone on progressive development of dysglycemia.

To examine the effect of total testosterone on development of pre-diabetes/diabetes in normoglycemic middle-aged and older men.

Data were obtained from the Tehran Lipid and Glucose Study, a community-based prospective cohort of an Iranian population. Analyses were conducted on 903 normoglycemic eligible men aged 30-70 years. An illness-death model was applied to estimate the probabilities of three transitional phases of normoglycemia→diabetes, normoglycemia→pre-diabetes, and pre-diabetes→diabetes.

Over a median follow-up of 12 years, 0.9% individuals developed diabetes. Per unit increase (ng/mL) in testosterone concentration, the transition rate from normoglycemia to pre-diabetes decreased by 6% [hazard ratios (HRs): 0.94 (95% confidence interval (CI): 0.90, 0.99)]. However, no effect for testosterone on the progression of diabetes from normoglycemia or pre-diabetes was observed [HRs: 0.79 (95% CI: 0.44, 1.41) and 0.98 (95% CI: 0.84, 1.16), respectively]. High body mass index was a strong predictor of hyperglycemia within all transitions.

Independent of major confounding factors, low testosterone was associated with normoglycemia progression to pre-diabetes, but not with pre-diabetes to diabetes, which might indirectly highlight the stronger impact of other risk factors after occurrence of pre-diabetes.

Low testosterone concentrations in men are associated with progression from normoglycemia to pre-diabetes, but not from pre-diabetes to diabetes.