Sex Differences in the Effect of Testosterone on Adipose Tissue Insulin Resistance From Overweight to Obese Adults

Objective Adipose tissue distribution and glucose metabolism differ between men and women. Few studies have investigated sex differences in adipose tissue insulin resistance (adipose-IR). Herein, we investigated sex differences in adipose-IR in adults ranging from overweight to obese and the potential factors associated with sex differences in adipose-IR. Methods A total of 424 adults had their body mass index (BMI), adipose-IR, and sex hormones evaluated. Based on BMI, males and females were assigned to 4 groups. Results In total, males (n = 156) had higher adipose-IR than females with similar BMI levels (n = 268) (P < 0.05). Adipose-IR progressively increased from overweight to class III obesity in both males and females (all P < 0.0001); however, only in the class III obesity group was the adipose-IR significantly higher in males than in females (P = 0.025). There were significant differences in testosterone between males and females (all P < 0.01); testosterone levels were negatively correlated with adipose-IR (r = -0.333, P < 0.001) in males but positively correlated with adipose-IR (r = 0.216, P < 0.001) in females. For the logistic regression analysis, testosterone was an independent protective factor against adipose-IR in males, with an odds ratio of 0.858 (B = -0.153 [95% CI, 0.743-0.991], P = 0.037). Conclusions Adipose-IR reflects the progressive deterioration in adipose tissue insulin sensitivity from overweight to obesity in both males and females. Males with class III obesity have more severe adipose-IR than similarly obese females. The sex difference is associated with testosterone, and low testosterone levels may contribute to more severe adipose-IR in obese males.