Serum testosterone level is known to inversely correlate with insulin sensitivity and obesity in men. Furthermore, there is evidence to suggest that testosterone replacement therapy reduces insulin resistance and visceral adiposity in Type 2 diabetic men. Adipocytokines are hormones secreted by adipose tissue and contribute to insulin resistance. We report a double-blind placebo controlled crossover study in 20 hypogonadal Type 2 diabetic men examining the effect of testosterone replacement therapy on adipocytokines and CRP. Patients were treated with testosterone (Sustanon 200 mg) IM every 2 weeks or placebo for 3 months in random order followed by a wash-out period of 1 month before the alternate treatment phase. At baseline, leptin levels significantly correlated with BMI (r=0.71; P<0.001) and waist circumference (r=0.78; P<0.001). There was also a significant inverse correlation between IL-6 levels and total testosterone (r=−0.68; P=0.002) and bioavailable testosterone levels (r=−0.73; P=0.007). CRP levels also correlated significantly with total testosterone levels (r=−0.59; P=0.01). Testosterone treatment reduced leptin (−7141.9±1461.8 pg/ml; P=0.0001) and adiponectin levels (−2075.8±852.3 ng/ml; P=0.02). There was a significant reduction in waist circumference (−2.1±0.81 cm; P=0.02). No significant effects of testosterone therapy on resistin, TNF alpha, IL-6 or CRP levels were observed.
In conclusion, testosterone replacement treatment decreases leptin and adiponectin levels in Type 2 diabetic men. Moreover, low levels of testosterone in men are associated with inflammation, though testosterone treatment over 3 months had no effect on inflammatory markers.