Low Testosterone in Men With Type 2 Diabetes: The Role of Estrogen Excess and Aromatase Activity

OBJECTIVE: Low testosterone is common in men with type 2 diabetes and is associated with adverse metabolic outcomes. Our objective was to identify factors associated with low total and calculated free testosterone (CFT) in men with type 2 diabetes, with a focus on relative estrogen excess and subcutaneous adipose aromatase expression. DESIGN: Cross-sectional study. PATIENTS: One hundred eighty men with type 2 diabetes and 92 healthy men in the reference cohort. MEASUREMENTS: Sex steroid hormones were measured alongside body composition, metabolic biomarkers, adipose tissue aromatase gene expression, and genetic variants of aromatase. T-scores for testosterone and estradiol were calculated using a healthy reference cohort. RESULTS: HbA1c (p < 0.001), BMI (p = 0.007), leptin (p = 0.009) and insulin resistance (p = 0.026) were associated with lower total testosterone (