SERUM LEPTIN IN SUBJECTS WITH IMPAIRED GLUCOSE-TOLERANCE IN RELATION TO INSULIN SENSITIVITY AND FIRST-PHASE INSULIN-RESPONSE

OBJECTIVE: It has been suggested that insulin could regulate the secre tion of leptin, the ob gene product, but the findings have been contra dictory. Therefore, we studied the association between leptin and insu lin secretion and insulin sensitivity in impaired glucose tolerance (I GT). SUBJECTS: 39 obese subjects (17 men, 22 women, body mass index (B MI) 30.6+/-0.6 kg/m(2), age 54+/-1 y, mean+/-s.e.m.) with IGT. MEASURE MENTS: Leptin, insulin sensitivity and first-phase insulin response (f requently sampled intravenous glucose tolerance test), anthropometry, infrared densitometric assay. RESULTS: Leptin correlated with BMI (r=0 .36, P=0.022), fat percent (r=0.74, P<0.001) and fat mass (r=0.53, P<0 .001). After adjustment for sex and fat mass, leptin showed no signifi cant linear correlation with fasting insulin, insulin sensitivity or f irst-phase insulin response. CONCLUSION: In obese IGT subjects fat mas s is the main correlate of serum leptin concentration. First-phase ins ulin response or the degree of insulin resistance are not associated w ith leptin in IGT.