Endocrine Abstracts

Introduction: Low testosterone serum levels are associated with increased mortality in non-diabetic males. However, knowledge about the association between male hypogonadism and mortality among type 2 diabetic (T2DM) men is limited due to short follow-up periods in the few existing studies.

Objective: To assess the association between hypogonadism and mortality in diabetic men.

Material and methods: 263 unselected men with T2DM (mean age 63.9±10.5 years) were followed prospectively until death or December 1, 2017, during a period of 8±3.9 years. Diagnosis of hypogonadism was established adding low total testosterone (TT) serum levels and hypogonadal symptoms (positive ADAM questionnaire). Three different thresholds for low testosterone were used (TT <3.4, <3 and <2.3 ng/ml). The survival in hypogonadal vs eugonadal men was analyzed with Kaplan-Meier survival curves (univariate analysis) and Cox regression (multivariate analysis).

Results: A total of 56 patients (21.3%) died during follow-up. Lower levels of TT (3.9 vs 4.4 ng/ml, P=0.044), free testosterone (7 vs 8.9 ng/dl; P=0.011) and bioavailable testosterone (164.2 vs 218.9 ng/dl; P=0.003) were found in deceased diabetic patients than in the group of survivors. The percentage of patients who died was higher in the hypogonadal group than in eugonadal diabetic men for all three thresholds (TT<3.4 ng/ml: 31.4 vs 17.7%, P=0.026, OR=2.1 (95% CI =1.1–4); TT<3 ng/ml: 33.3 vs 18.8%, P=0.044, OR=2.2 (95% CI =1.1–4.4); TT<2.3 ng/ml: 46.7% vs 18%, P=0.001, OR=4 (95% CI =1.8–8.8)). Survival was significantly lower in hypogonadal than in eugonadal men, and that was also demonstrated by using the three thresholds: TT<3.4 ng/ml: 68.6% vs 82.7% (Log-rank 8.5, P=0.004); TT<3 ng/ml: 66.7% vs 81.6% (Log-rank 7.7, P=0.005) and TT<2.3 ng/ml: 53.3% vs 82.3% (Log-rank 21.4, P< 0.001). In addition, the mean time of survival was lower in hypogonadal than in eugonadal men (TT<3.4 ng/ml: 11.3 vs 14.3 years, P=0.004; TT<3 ng/ml: 11 vs 14.1 years, P=0.005 and TT<2.3 ng/ml: 7.7 vs 14.2 years, P<0.001). In the multivariate analysis, hypogonadism increased the risk of mortality (HR=2.3, 95% CI =1.2–4.3, P=0.01) independently of age, poor glycemic control, renal failure and the presence of macrovascular disease.

Conclusions: In the longest follow-up study reported so far we show that hypogonadism is associated with decreased survival in diabetic men. Mortality rates and mean time of survival were associated with the severity of male hypogonadism.