Testosterone, obesity and insulin resistance in young males: evidence for an association between gonadal dysfunction and insulin resistance during puberty.

Objective: To assess the relationships among obesity, insulin sensitivity, and testosterone in pubertal boys. Participants: This study included 20 lean, obese, and type 2 diabetic (T2DM) males, the majority of whom underwent a hyper-insulinemic-euglycemic clamp (n=16). Methods: Glucose disposal (M value), serum testosterone, and body mass index (BMI) z-score were measured. Differences in testosterone were evaluated by group (lean vs. obese vs. T2DM), while regression was performed to evaluate the relationships among testosterone, obesity and insulin sensitivity. Results: Controlling for Tanner stage, testosterone concentration was significantly lower in obese (p=0.02) and T2DM males (p=0.001) compared to lean males. Furthermore, M value was significantly associated with serum testosterone, even after controlling for BMI and Tanner stage. Conclusions: These data suggest that obese adolescent boys have lower serum testosterone than controls of the same Tanner stage, and echo the data in adult males associating obesity and insulin resistance with hypogonadism.