UroToday - In the online edition of the Journal of Andrology, Dr. Abdulmaged M. Traish and associates reviewed the evidence linking decreased plasma levels of testosterone, type 2 diabetes (T2D), and insulin resistance (IR). They performed a literature search to generate the data in this review, and concluded that androgen deficiency is linked with T2D, IR, metabolic syndrome (MetS), and increased visceral fat deposition, which serves as an endocrine organ, producing inflammatory cytokines that promote endothelial dysfunction and vascular disease. Some of the interesting supporting data are as follow.

The prevalence of T2D has increased in the US and mirrors the increased prevalence in obesity. A systematic review by Ding in 6,426 men suggests that higher testosterone levels are associated with a lower risk of T2D and vice versa. Low sex hormone binding globulin and testosterone predict higher glucose and insulin levels and increased obesity. Another study found that low levels of testosterone and sex hormone binding globulin played a role in the development of IR and T2D. There is also an inverse relationship between total testosterone and IR. Lower total testosterone leads to elevated insulin values, and body fat distribution may influence this relationship, although that is not proven. Thus, testosterone may have a protective function against diabetes in men.

Hypogonadism and T2D are often diagnosed together in the same patient. Above the age of 50, the prevalence of hypogonadism increases with 55% of men between 70 and 79 having hypogonadism compared to 24% in the 50-59 year age group. Individuals with a body mass index of >30 had significantly higher fasting plasma insulin, fasting IR index, C-peptide and lower serum testosterone than men with a BMI