Hypogonadotropic Hypogonadism in Type 2 Diabetes and Obesity
Paresh Dandona and Sandeep Dhindsa wrote this update on hypogonadotropic hypogonadism (HH) in type 2 diabetes and obesity. They review current literature and offer suggestions for further research to advance understanding of acquired HH.
Prevalence of HH
Several studies over the last few years have confirmed that HH is present in 25-40% of men with type 2 diabetes. Because of this high prevalence, The Endocrine Society has made recommendation to measure testosterone levels in all male patients with type 2 diabetes.
Dandona and Dhindsa used liquid chromatography tandem mass spectrometry assay. The reference ranges for total and free testosterone have been adjusted downward, and Dandona and Dhindsa used these new ranges to estimate HH prevalence. They found HH to be present in 25% of men with type 2 diabetes.
Another 4% of men had hypergonadotropic hypogonadism (subnormal testosterone with elevated LH and FSH concentrations).
What Is Subnormal Testosterone Associated With?
Subnormal testosterone is not related to glycosylated hemoglobin or duration of diabetes. It is associated with:
- very high C-reactive protein concentrations
- mild anemia
- increased prevalence of symptoms of hypogonadism
- decreased BMD
Two earlier studies showed that men with low testosterone are at a 2 to 3 times elevated risk for cardiovascular events and death.
Effects of Testosterone Therapy
Men receiving testosterone therapy have shown an increase in insulin sensitivity, as well as a decrease in waist circumference.
They have also shown an increase in libido but not an improvement in erectile dysfunction; phosphodiesterase inhibitors may be needed.
Data are mixed on the effect of testosterone therapy on glycemic control and cardiovascular risk.
Further Study Needed
Dandona and Dhindsa suggest that more trials—particularly those of longer duration—are needed in order to better understand the risks and benefits of testosterone therapy for patients with subnormal testosterone and type 2 diabetes.
Due to the high prevalence of hypogonadotropic hypogonadism (HH) in patients with type 2 diabetes, two of the experts in this area have evaluated this unique population and made recommendations for screening and treatment.
Using a liquid chromatography tandem mass spectrometry assay, they found the prevalence of HH to be 25%. The presence of subnormal testosterone levels has been associated with obesity, mild anemia, high CRP, low bone mineral density, and increased symptoms of hypogonadism. It is not, however, associated with hemoglobin A1c levels or duration of diabetes diagnosis.
Type 2 diabetics with hypogonadism who receive testosterone therapy have shown improved insulin sensitivity, decreased waist circumference, and increased libido. It remains unclear whether there is an improvement in glycemic control or cardiovascular risk with treatment. More studies of longer duration are warranted to better characterize and describe the risks and benefits of testosterone therapy in this population.