Testosterone and leptin in a group of Chinese with and without diabetes

Leptin levels in the overweight and differences between men and women may be confounded by sex hormones in obesity-related type 2 diabetes. We carried out a study of leptin and testosterone and the effect of diabetes on this relationship in 71 Chinese subjects (51 with type 2 diabetes and 20 healthy non-diabetics) of whom 32 were overweight (body mass index (b.m.i.) > 25.0 kg/m2).

Leptin levels were similar in the diabetic (median 7.4, interquartile range 4.2-10.6 ng ml-1) and non-diabetic (11.3 (6.0-16.3) ng ml-1) subjects. Testosterone and free testosterone in diabetics and non-diabetics were similar for both gender. Regardless of diabetes status, testosterone and its free form tend to increase in overweight women and decrease in men. Leptin correlated with testosterone in women with diabetes (Pearson correlation coefficient r = 0.495, p = 0.037) but not in diabetic men. Sixty-eight per cent of leptin variance was affected by b.m.i, insulin, sex (female) and diabetes status in a regression model that excluded testosterone (total and free). However, testosterone and insulin were predictors of leptin changes in the non-diabetic subjects. In diabetes, b.m.i., sex (female) and insulin remained as predictors of leptin changes.

These results suggest that apart from body adiposity, testosterone also influences leptin levels and that diabetes has a significant effect on this association.