It is well known that diabetes affects erectile function. Diabetes causes changes to the endothelium and penile vascular system.
What is lesser known is that men with type 2 diabetes also have higher prevalence of testosterone deficiency and a higher mortality rate. In fact, testosterone deficiency in men precedes the development of insulin resistance and diabetes. Low levels of testosterone in men can lead to lower libido and poor erectile function.
A six-year study conducted in the UK on 518 men demonstrated a bidirectional relationship between obesity, metabolic syndrome, diabetes, insulin resistance, and testosterone deficiency. The study also found that testosterone replacement therapy could delay or prevent many of these conditions.
There is other data supporting a direct role of testosterone in insulin sensitivity. In one study, men who had lower than average testosterone levels were taken off testosterone replacement therapy. After two weeks, these men showed an increase in insulin sensitivity without apparent changes in body composition. This suggests that sex steroids have a direct effect in modulating insulin sensitivity, which also affects erectile function. Other studies have demonstrated the interplay between insulin sensitivity, triglycerides, and sex steroids. The effects of testosterone is immediate and not due to weight gain or increased obesity.
If you have type 2 diabetes, the next time you see your physician ask about your testosterone levels to find out if testosterone replacement therapy is right for you.