Since published studies have involved imprecise assays and selected patients with limited additional data and follow-up, the consequences of a low serum testosterone in diabetes are unclear. The present study assessed the prevalence, associates and prognosis of a low testosterone in community-dwelling men with type 2 diabetes.
Longitudinal observational study.
788 (mean±SD age 65.8±11.3 years) followed for 4.0±1.1 years.
Serum testosterone, SHBG, erectile dysfunction (ED; Sexual Health Inventory for Men score <22), anaemia (haemoglobin <130 g/L), all-cause mortality.
The mean±SD total serum testosterone by liquid chromatography/mass spectrometry was 13.1±5.9 nmol/L (30.6% <10 nmol/L). Most men with a total testosterone <10 nmol/L (67.0%) had a normal/low serum LH. Serum testosterone was independently associated with anaemia (P<0.001) but not ED (P=0.80) in logistic regression models. The optimal cut-point (Youden Index) for anaemia was 9.8 nmol/L (sensitivity 53.6%, specificity 75.4%). During follow-up, 102 men (12.9%) died. There was a U-shaped relationship between total serum testosterone quintiles and death (P=0.003, log rank test). The middle quintile (>11.1 to ≤13.7 nmol/L) had the lowest risk and there was a 78% increased risk for highest (>16.9 nmol/L) vs lowest (≤8.6 nmol/L) quintile in Cox proportional hazards modelling (P=0.036). Free serum testosterone and SHBG quintiles were not associated with death.
These data provide some support for the general conventional serum testosterone <10 nmol/L cut-point in identifying an increased risk of anaemia and subsequent death in men with type 2 diabetes but indicate that high-normal levels are also an adverse prognostic indicator. This article is protected by copyright. All rights reserved.
Clinical endocrinology. 2016 Apr 23 [Epub ahead of print]
Emma J Hamilton, Wendy A Davis, Ashley Makepeace, Ee Mun Lim, Bu B Yeap, Kirsten E Peters, Timothy Me Davis
University of Western Australia, School of Medicine and Pharmacology, Crawley, Western Australia, Australia., University of Western Australia, School of Medicine and Pharmacology, Crawley, Western Australia, Australia., University of Western Australia, School of Medicine and Pharmacology, Crawley, Western Australia, Australia., Department of Biochemistry, PathWest Laboratory Medicine WA, Sir Charles Gairdner Hospital, Nedlands, Australia., University of Western Australia, School of Medicine and Pharmacology, Crawley, Western Australia, Australia., University of Western Australia, School of Medicine and Pharmacology, Crawley, Western Australia, Australia., University of Western Australia, School of Medicine and Pharmacology, Crawley, Western Australia, Australia.