Hypogonadotropic Hypogonadism in Erectile Dysfunction Associated with Type 2 Diabetes Mellitus: A Common Defect?

The objective of this study was to evaluate the gonadal function in men with type 2 diabetes with erectile dysfunction. Methods: We examine records of 50 patients with type 2 diabetes and erectile dysfunction who had low free testosterone concentrations. All patients had plasma concentrations of luteinizing hormones (LH), follicle-stimulating hormone (FSH), and prolactin measured. Results: Of the 50 patients with low free testosterone concentrations (0.97 +/- 0.4 ng/dL; reference range, 1.30-3.10), 43 had normal (inappropriately low) LH (5.9 +/- 2.9 mIU/mL), FSH (5.6 +/- 2.4 mIU/mL), and testosterone concentrations, five had elevated LH, FSH concentrations (Hypogonadotropic hypogonadism), and two had prolactinoma. Patients with hypogonadotropic hypogonadism were in their mid 50's and had experienced a decline in their testosterone levels much earlier than that expected from the normal age-related decline. Although a majority of the patients were obese, there was no relationship between testosterone (free or total) and BMI, between testosterone and HbA(1c), duration of diabetes or the age of the patient. Patients given testosterone supplementation experienced a subjective improvement in their well-being, but reported no significant improvement in their erectile dysfunction. Conclusion: We conclude that patients with erectile dysfunction require careful assessment and that the most frequent gonadal defect in these patients is that of hypogonadotropic hypogonadism, a defect not previously associated with type 2 diabetes. The mechanism underlying this defect requires investigation. The value of testosterone replacement in such patients needs to be assessed critically.