Analysis of the relationship between fasting serum leptin levels and estimates of beta-cell function and insulin sensitivity in a population sample of 380 healthy young Caucasians

Objective: Circulating leptin levels correlate positively with the degree o f obesity and prolonged hyperinsulinaemia increases serum leptin levels. Mo reover, insulin secreting beta-cells express functional leptin receptors in dicating a functional relationship between leptin and insulin. The aim of t his study was to examine the relationship between fasting serum leptin leve ls and measures of insulin sensitivity and beta-cell function in a populati on-based sample of 380 young healthy Caucasians. Design and Methods: Multiple regression analysis was employed to analyse th e relationship between fasting serum leptin levels and levels of fasting se rum insulin, insulin sensitivity index and acute insulin response (AIR) in a population-based study of 380 young healthy Caucasians who underwent a co mbined intravenous glucose and tolbutamide tolerance test. Results and Conclusion: Serum leptin levels were positively correlated to m easures of adiposity and were 3.2 times higher in women than in men (P<0.00 001). In multiple regression analyses adjusting for age, percentage body fa t, waist circumference and maximal aerobic capacity, a significant positive correlation was observed between the fasting serum leptin concentrations a nd both fasting serum insulin levels (P<0.0001) and AIR (P=0.014) for women . No significant interrelation of these variables was found in men. However , for both genders a significant negative correlation was observed between fasting serum leptin levels and measures of insulin sensitivity index (P = 0.007).