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 >= 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.