Effect of testosterone replacement therapy on insulin sensitivity and body composition in congenital hypogonadism: A...

To evaluate the prevalence of metabolic syndrome (MS) and whole-body composition in patients with congenital hypogonadism and investigate the effects of replacement therapy with testosterone undecanoate on MS, insulin resistance (IR), and whole-body composition in subset of patients.

In a single arm prospective longitudinal intervention study, 33 patients with congenital hypogonadism, ages 20-39 years, were recruited and their parameters of MS, whole-body composition by DXA were compared with age and BMI matched healthy controls. In 21 patients, after 9 months we prospectively studied the effect (pre-post difference) of injection testosterone undecanoate (1,000 mg) replacement on MS, IR, and whole-body compositions.

The prevalence of MS was similar in patients and controls (27.3% vs. 9.1%, P = 0.05). Hypogonadism patients had higher prevalence of hypertension (33% vs. 3%, P < 0.01). Patients had decrease in lean body mass (P < 0.05) as compared to controls. After testosterone replacement, there was significant decrease in waist circumference (88.6 ± 13.1 cm vs. 83.9 ± 12.9 cm, P < 0.01), truncal fat (25.9 ± 7.3% vs. 24.0 ± 6.3%, P < 0.05), fasting C-peptide (2.1 ± 0.79 ng/ml vs. 0.68 ± 0.23 ng/ml, P < 0.01), serum proinsulin [1.43 (0.32-13.4) vs. 0.5 (0.5-3.2) pmol/l, P < 0.001] and a significant increase in lean body mass (46,906 ± 8,876 gm vs. 50,083 ± 7,590 gm, P < 0.001). Homeostasis model assessment of insulin resistance (HOMA-IR) (4.6 ± 1.7 vs. 0.5 ± 0.2, P < 0.001) and homeostatic model for assessment of insulin sensitivity (HOMA%S) [21 (12-65) vs. 206 (125-714), P < 0.001] were improved significantly following testosterone replacement.

In this study, 36 weeks of testosterone replacement resulted in significant decrease in waist circumference, IR, truncal fat, total body fat and improvement in lean body mass, and insulin sensitivity.