The Correlation between 25-Hydroxyvitamin D Levels and Testosterone Levels in Type 2 Diabetic Male Patients.

Abstract

Hypovitaminosis D and low testosterone levels are common in men with T2DM, and vitamin D has been proposed to regulate pituitary-testicular function. We investigated the association between testosterone levels and the circulating vitamin D among type 2 diabetic males. We recruited 95 type 2 diabetic males in this cross-sectional study, and investigated the circulating form of vitamin D which is 25-hydroxyvitamin D (25(OH) D). 25(OH) D level <30 ng/mL was used to define vitamin D insufficiency and 25(OH) D level <20 ng/ml defined deficiency. Testosterone deficiency was defined as a total testosterone level less than300 ng/dl. Testosterone deficiency prevalence in type 2 diabetic males was 46.3%. Testosterone deficient diabetics had significantly lower 25(OH) D levels than patients with normal testosterone. We observed a higher prevalence of vitamin D deficiency in testosterone deficient diabetics compared with testosterone sufficient patients. Furthermore, significantly lower total testosterone but not LH levels were observed in diabetic males with vitamin D deficiency in comparison to non-deficient patients. We observed that 25(OH) D significantly predicted total testosterone levels in diabetic males evaluated by linear regression analysis. However this association was no longer statistically significant after exclusion of macro-albuminuric patients. Moreover, Vitamin D deficiency was a significant risk factor for testosterone deficiency in logistic regression analysis. Testosterone deficient diabetic males had significantly lower 25(OH)D levels and a higher prevalence of vitamin D deficiency in comparison with normal testosterone diabetic males. Likewise, vitamin D deficient patients had lower testosterone levels. Overall, 25(OH) D significantly predicted total testosterone levels. The vitamin D deficiency was thus a significant risk factor for testosterone deficiency in diabetic males.