Impact of testosterone therapy on bone turnover markers in obese males with type 2 diabetes and functional hypogonadism

Methods Fifty-five obese males with type 2 diabetes mellitus and functional hypogonadism participated in a 2-year, double-blind, placebo-controlled study of testosterone undecanoate (TU). Bone turnover markers C-telopeptide of type I collagen (CTX) and procollagen I N-terminal propeptide (PINP) were assessed at baseline, 12 and 24 months. Bone mineral density (BMD) changes were evaluated after 24 months using dual-energy X-ray absorptiometry. Group T (n = 28) received TU both years. Group P (n = 27) received placebo first year and TU second year. Results CTX decreased in group P from 1055 (676-1344) to 453 (365-665) pmol/L (p < 0.001) and from 897 (679-1506) to 523 (364-835) pmol/L (p < 0.001) in T. PINP decreased by 4.30 +/- 8.05 mu g/L in group P (p = 0.030) and 4.64 +/- 8.86 mu g/L in T (p < 0.023) after first year of therapy. No femoral neck BMD changes were observed in 32 patients from both groups (n = 16 per group). Lumbar spine BMD increased (by 0.075 +/- 0.114 g/cm(2); p = 0.019) in group T following two years of treatment. Conclusions We observed decreased CTX, decreased PINP and increased lumbar spine BMD after two years of testosterone treatment.