title: Testosterone level in men with type 2 diabetes mellitus and related metabolic effects: A review of current evidence.
abstract: A significant proportion of patients with type 2 diabetes mellitus have a low testosterone level relative to reference ranges based on healthy young men. Only a small number of these patients suffer from classical hypogonadism as a result of recognizable hypothalamic-pituitary-gonadal axis pathology. The cut-off value of the serum testosterone level in men without obvious hypothalamic-pituitary-gonadal axis pathology is controversial. It is unclear to what extent a low serum testosterone level causally leads to type 2 diabetes and/or the metabolic syndrome. From a theoretical standpoint, there can be complex interactions among the hypothalamic-pituitary-gonadal axis, body composition and insulin resistance, which can be further influenced by intrinsic and extrinsic factors to give rise to metabolic syndrome, glucose intolerance, and low-grade inflammation to increase the risk of cardiovascular disease. Although a low serum testosterone level frequently coexists with cardiometabolic risk factors and might serve as a biomarker, more studies are required to clarify the causal, mediating or modifying roles of low serum testosterone level in the development of adverse clinical outcomes. Currently, there are insufficient randomized clinical trial data to evaluate the effects of testosterone replacement therapy on meaningful clinical outcomes. The risk-to-benefit ratio of testosterone therapy in high-risk subjects, such as those with type 2 diabetes, also requires elucidation. The present article aims to review the current evidence on low serum testosterone levels in patients with type 2 diabetes, and its implications on cardiovascular risk factors, metabolic syndrome and adverse clinical outcomes.
authors: Department of Medicine and Therapeutics, Hong Kong Institute of Diabetes and Obesity, The Chinese University of Hong Kong, Prince of Wales Hospital New Territories, Hong Kong SAR, China.
authors: Kitty Kit Ting
authors: KK
authors: Cheung
authors: Department of Medicine and Therapeutics, Hong Kong Institute of Diabetes and Obesity, The Chinese University of Hong Kong, Prince of Wales Hospital New Territories, Hong Kong SAR, China.
authors: Andrea On Yan
authors: AO
authors: Luk
authors: Department of Medicine and Therapeutics, Hong Kong Institute of Diabetes and Obesity, The Chinese University of Hong Kong, Prince of Wales Hospital New Territories, Hong Kong SAR, China.
authors: Wing Yee
authors: WY
authors: So
authors: Department of Medicine and Therapeutics, Hong Kong Institute of Diabetes and Obesity, The Chinese University of Hong Kong, Prince of Wales Hospital New Territories, Hong Kong SAR, China.
authors: Ronald Ching Wan
authors: RC
authors: Ma
authors: Department of Medicine and Therapeutics, Hong Kong Institute of Diabetes and Obesity, The Chinese University of Hong Kong, Prince of Wales Hospital New Territories, Hong Kong SAR, China.
authors: Alice Pik Shan
authors: AP
authors: Kong
authors: Department of Medicine and Therapeutics, Hong Kong Institute of Diabetes and Obesity, The Chinese University of Hong Kong, Prince of Wales Hospital New Territories, Hong Kong SAR, China.
authors: Francis Chun Chung
authors: FC
authors: Chow
authors: Department of Medicine and Therapeutics, Hong Kong Institute of Diabetes and Obesity, The Chinese University of Hong Kong, Prince of Wales Hospital New Territories, Hong Kong SAR, China.
authors: Juliana Chung Ngor
authors: JC
authors: Chan
keywords: Metabolic syndrome; Testosterone; Type 2 diabetes