Leptin Indicates Obesity and Insulin Resistance in Men

抄録

Background Leptin, a product of the obese (ob) gene, is released from adipocytes. Plasma leptin is correlated with both obesity and plasma insulin (immunoreactive insulin, IRI), and at the same body mass index (BMI) there is considerable variation in plasma leptin concentrations. However, it is not clear whether plasma leptin is correlated with plasma insulin at the same BMI. This study was designed to determine the relationship between plasma leptin and insulin resistance after adjustment for BMI.
Methods A cross-sectional study was carried out using 423 healthy overweight people aged 40-65 years (342 men and 81 women, BMI≥22 kg/m2). Subjects were divided into three groups by plasma leptin concentrations (<25 percentile,25-<75 percentile, ≥75 percentile) after adjusting for BMI. Weight, height, leptin, IRI, and blood pressure were studied after an overnight fast. Insulin sensitivity was modeled according to a homeostasis model assessment of insulin resistance (HOMA-IR). Analysis of variance (ANOVA) with Dunnett's t-test were used to compare results between groups.
Results Eighty men and 18 women belonged to the low group (<25 percentile),173 men and 40 women to the middle group (25-<75 percentile), and 89 men and 23 women to the high group (≥75 percentile). The results were evaluated using one-way ANOVA and Dunnett's t-test (vs. the middle group). HOMAIR, fasting IRI, and systolic and diastolic blood pressure were higher only among men, in the high group compared to those in the middle group.
Conclusion A relatively high plasma leptin concentration after adjustment for BMI might indicate insulin resistance in men.