Testosterone levels in males with type 2 diabetes and their relationship with cardiovascular risk factors and cardiovascular disease.

Introduction: One of the factors involved in type 2 diabetes in males is a reduction in levels of testosterone, which has been shown to predict resistance to insulin and the development of cardiovascular diseases.

Aim: To assess the levels of testosterone in patients with type 2 diabetes and to evaluate their relationship with cardiovascular risk factors, peripheral arterial disease (PAD) and silent myocardial ischemia (SMI).

Methods: Total testosterone and sex hormone binding globulin were measured and free and bioavailable testosterones were calculated using Vermeulen's formula. Levels of total testosterone > or = 12 nmol/L or free testosterone > 225 pmol/L were considered normal. PAD was evaluated using the ankle-brachial index. SMI was assessed using a baseline ECG, Doppler echocardiogram, 24-hour electrocardiogram (ECG) Holter, exercise stress testing (EST), nuclear stress (if EST inconclusive), and if the result was positive, a coronary angiography.

Main Outcome Measures: PAD, SMI, testosterone, erectile dysfunction, 24-hour blood pressure Holter, body mass index (BMI), waist circumference, lipid profile, insulin resistance, chronic inflammation, United Kingdom Prospective Diabetes Study cardiovascular risk score, nephropathy, retinopathy, and neuropathy.

Results: The study population was composed of 192 diabetic males with a mean age of 56.1 +/- 7.8 years and without a history of vascular disease. Twenty-three percent presented total testosterone below normal and 21.8% presented low free testosterone. BMI, waist circumference, neuropathy, triglycerides, C-reactive protein (CRP), glucose, insulin, and HOMA-IR were found to be significantly incremented with respect to subjects with normal testosterone. There was a negative correlation of HOMA-IR with total testosterone. PAD was detected in 12% and SMI in 10.9% of subjects, and differences were not related to testosterone levels.

Conclusions: We have verified the prevalence of low testosterone levels in male patients with type 2 diabetes and have related them to variations in BMI, waist circumference, neuropathy, triglycerides, CRP, glucose, insulin and HOMA-IR, but not with an increase of SMI or PAD.