Background: Low testosterone in men is associated with increase in all-cause and cardiovascular mortality. There is a high prevalence of hypogonadism in men with type 2 diabetes and testosterone replacement therapy (TRT) improves cardiovascular risk. However there is no published data regarding mortality in these patients in relation to testosterone levels, and the long term effect of TRT on mortality.
Aim: We report a 6 year follow-up study examining the effect of baseline testosterone and TRT in hypogonadal men with type 2 diabetes on all-cause mortality.
Methods: Five hundred eighty-seven patients with type 2 diabetes had total testosterone (TT) performed between 2002 and 2005 and were followed up for 5.8±1.3 years.
Deaths during the first 6 months were excluded. Patients were then analysed in three groups. i) normal TT (>10.4 nmol/l) ii) low TT (≤10.4 nmol/l) without TRT. iii) low TT receiving TRT for 2 years or more.
Results: Of 580 patients analysed, 338 had normal TT (58%) and 240 low TT (42%). In the low TT group 58 patients received TRT. Mean age 61±11 S.D. and similarly matched in all three groups. Total deaths 72 (12.4%). Mortality rates low TT without treatment (36/182-20%), normal TT (31/338-9%) and low TT with TRT (5/58-8.6%). Survival was significantly decreased in patients with low TT without TRT (P=0.001 log rank) compared to normal. The treated group had improved survival (P=0.049 log rank). In the Cox Regression model multi-variate (age, weight, HbA1c, pre existing cardiovascular disease, smoking, statin and ACEi/ARB use) adjusted hazard ratio for all-cause mortality was 2.2 (95% CI 1.33.7 P=0.001) for low TT.
Conclusions: This study shows that men with type 2 diabetes and low testosterone have a significant increased mortality. TRT improved survival compared to those untreated, recording a similar mortality rate to the normal TT group.