Partial androgen deficiency in aging type 2 diabetic men and its relationship to glycemic control

Abstract

Aging in the male is associated with both a higher incidence of type 2 diabetes and hypogonadism. However, little information is available about the complex of symptoms and hormonal changes related to partial androgen deficiency in aging (called andropause) in type 2 diabetic men. Here, for the first time, we used a combination of clinical and hormonal criteria to define andropause and to analyze the relationships between the androgen environment and glucose metabolism in 55 type 2 diabetic men (63.6 ± 7.9 years, mean ± SD). Low plasma levels of total testosterone (≤3.4 ng/mL) and free testosterone (≤11 pg/mL) were found in 20% and 54.5%, respectively, of the diabetic men. The fraction of diabetic men with subnormal levels of total testosterone increased with aging: 14.2% (50 to 59 years), 17.4% (60 to 69 years) and 36% (> 70 years). The corresponding figures for subnormal values of free testosterone were 38%, 69.6%, and 54.5%, respectively. In the whole group of type 2 diabetic men, no significant linear correlations between total or free testosterone with fasting plasma glucose, insulin, C-peptide, or fructosamine values could be established. Total testosterone was positively correlated with glycosylated haemoglobin (HbA 1c) levels ( r = .322, P = .01). Although fasting plasma glucose was marginally higher in aging type 2 diabetic patients with andropause than in those without andropause (162 ± 6.9 v 139 ± 8.9, mean ± SEM, P = .05), there were no differences between both subgroups for plasma fasting insulin, C-peptide, fructosamine, or HbA 1c levels. Replacement therapy (150 mg intramuscular [IM] of enanthate of testosterone every 14 days for 6 months) was applied in 10 type 2 diabetic men with clinical features of andropause associated with subnormal concentrations of serum testosterone. The treatment induced significant increases in total plasma testosterone (baseline: 3.9 ± 0.3; at 6 months: 7.1 ± 0.9 ng/mL, mean ± SEM, P = .003) and free testosterone (baseline: 9.3 ± 0.6; at 6 months 17.6 ± 2.4 pg/mL, P = .003), but had a neutral effect on overall glycemic control. These data show a high prevalence of andropause in aging type 2 diabetic men and suggest that the endogenous androgen environment, as well as correction of the partial androgen deficiency, do not have a meaningful effect on glycemic control.