[Relationship between leptin and body mass and metabolic syndrome in an adult population].

Objective: To analyze the relationship between leptin and obesity expressed as body mass index (BMI) and certain components of the metabolic syndrome (MS) in an adult population.

Methods: The study included 103 subjects, 42 men and 61 women, aged over 30 years, clinically defined as non-diabetic but with personal or family history of cardiovascular disease. All subjects underwent fasting blood measurements of leptin, insulin, glucose, glucose after ingestion of 75g glucose, HDL cholesterol and triglycerides, and insulin resistance (IR) and BMI were calculated.

Results: BMI as an index of overall adiposity was strongly associated with serum leptin. BMI rose as serum leptin levels increased from the first to the third tertile; the correlation between leptin and BMI was strong, r=0.524 in men and r=0.603 in women, with high statistical significance (p<0.001); BMI was the best predictor of hyperleptinemia on ROC analysis, with area under the curve (AUC)=0.81 in men and 0.84 in women. The association between leptin and obesity (BMI ≥30kg/m(2)) showed high odds ratios (OR) in both sexes (10.11 in men, 6.00 in women) on univariate regression analysis and 9.30 in men and 8.21 in women on multivariate regression analysis. Hyperinsulinemia and IR strongly influenced hyperleptinemia. Leptin was the best predictor of IR in both sexes (AUC=0.89 in men and 0.85 in women), and IR in men (AUC=0.79) and hyperinsulinemia in women (AUC=0.78) were the best predictors of hyperleptinemia after BMI. The correlations between leptin and IR, and leptin and insulinemia, were strong in both sexes. With regard to MS components, increased serum levels of the study variables were observed as leptin concentrations rose from the first to the third tertile (with the exception of HDL cholesterol, which decreased).

Conclusion: Elevated serum leptin, particularly in obese individuals, should be taken as a warning sign of energy imbalance, poor diet, hyperinsulinemia, insulin resistance, or changes in other metabolic risk factors that are strongly associated with cardiovascular disease and type 2 diabetes.