Relations Between Body Fat Mass and Insulin Resistance in Non-Obese Patients with Idiopathic Hypogonadotropic Hypogonadism and Normal Glucose Tolerance

The purpose of this study was to investigate the relationship between body fat mass and insulin resistance in non-obese patients with idiopathic hypogonadotropic hypogonadism (IHH) and normal glucose tolerance. A total of 42 patients with IHH and normal glucose tolerance, and BMI lower than 28 kg/m (2) were recruited. Patients were required to have a normal glucose tolerance test for inclusion in the study. Ten Healthy subjects were recruited as control group. Laboratory studies included fasting insulin, testosterone, and lipids. Waist circumference (WC), weight, and body fat mass were measured, and waist-to-hip ratio (WHR), body mass index (BMI), HOMA-IR, and logHOMA-B were calculated. Data were compared between groups, and linear regression was used to determine relations. Blood pressure, fasting glucose, BMI, WHR, and lipids were similar between the groups. Fasting insulin levels (15.61 +/- 7.66 mIU/l vs. 7.60 +/- 3.84 mIU/l), logHOMA-B (2.39 +/- 0.29 vs. 2.03 +/- 0.21), HOMA-IR (3.38 +/- 1.71 vs. 1.64 +/- 0.91), and body fat mass (30.49 +/- 9.46% vs. 21.11 +/- 4.31%) were significantly greater in the IHH group compared with those in control group (all p<0.05). Multivariable linear regression showed that in IHH patients body fat mass was an independent predictor of fasting insulin level (beta=0.71, p<0.01), logHOMA-B (beta=0.02, p<0.05), and HOMA-IR (beta=0.14, p<0.05). Body fat mass is an independent predictor of insulin resistance in non-obese IHH patients with normal glucose tolerance.