Type 2 diabetes mellitus (T2DM) is often associated with obesity and subnormal serum testosterone (T) levels. Until 5 years ago there was no indication that men with type 1 diabetes mellitus (T1DM) had subnormal serum T. But recent studies indicate that about 10% of men with T1DM suffer from hypogonadism, as a rule aged men and men with obesity. While hypogonadal men with T2DM benefit from normalization of their serum T, this has not been investigated in men with T1DM. Nine men with T1DM, erectile dysfunction and hypogonadism (total testosterone ≤ 12 nmol/L) received testosterone replacement therapy (TRT). In seven men TRT was intermitted: one man with prostate malignancy and six men because of problems of reimbursement. Incidentally, this provided an opportunity to monitor the effects of withdrawal and of the reinstatement of TRT. In all men, glycemic control (serum glucose and HbA1c), weight, waist circumference, lipid profiles and erectile function improved upon TRT. The seven men whose TRT was intermitted showed a deterioration which improved again upon reinstatement of TRT. The data suggest that aging and obese men with T1DM might have subnormal T levels and that their glycemic control, lipid profiles and erectile function might benefit from TRT.
Keywords: Diabetes mellitus type 1; HbA1c; erectile function; glucose; hypogonadism; testosterone; waist circumference.