['To investigate the relationship between total osteocalcin (total OC) and testosterone level in the serum of male patients with type 2 diabetes mellitus (T2DM).', '98 male T2DM were recruited in our cross-section study. Their anthropometric parameters were measured and body mass index (BMI) was calculated. Serum markers including glucose, insulin, HbA1c, testosterone, total OC and other bone metabolic markers were examined. Simple Pearson correlation and multiple regression analysis were performed.', 'Poor level of glucose control was found in the patients (HbA1c 9.19±2.53 and FPG 8.20±2.98). In simple Pearson correlation, total OC was positively related with testosterone (r=0.236, P=0.019), and this relation still existed after considering all the parameters of the patients (Model 1, 2 and 3).'] Does total osteocalcin in serum predict testosterone level in male type 2 diabetes mellitus?