Aim: Leptin is a nonglycolyzed peptide, made of 146amino-acids, that is produced by ob-gene in fat tissue. Leptin in circulation shows its effects by inhibiting Neuropeptide-Y in central nervous system and shows its effects on body fat mass by decreasing appetite and increasing energy usage. Because of the unproportional relation between the leptin levels and weight loss, there must be some other factors other than body fat mass in its regulation. Starving and feeding have an influence on leptin levels. We aimed to evaluate the effect of acute glucose administration on circulating leptin levels.

Material and methods: 34 obese and 16 healthy volunteers (Group III) were included in the study and a75gr oral glucose tolerance test was applied to all cases. The cases were assigned according to the World Health Organization criteria as; cases who were obese and had impaired glucose tolerance were grouped as GroupI (n=12) and cases who were obese and had normal glucose tolerance were grouped as GroupII (n=22). During the oral glucose tolerance test, glucose and insulin analysis were performed on the blood samples taken from the patients at 0,-30,-60,-90 and,-120 minutes, and leptin analysis was performed on the blood samples at 0 and 120 minutes. The body mass index of the cases was calculated.

Results: The BMI of the cases was33.3±7.4kg/m2 in Group I, 38.5±7.4kg/m2 in Group II, and 22.8±2.6kg/m2 in Group III. Leptin levels were59.8±35.7ng/mL in Group I, while it was 69.67±22.5ng / mL in Group II and 26.6±20.2ng/mL in Group III.

Conclusion: There was a significant (p<0,05) difference in the leptin levels between the study groups (p<0.05)by ANOVA analysis, while no significant difference was found between the leptin levels of GroupI and GroupII (p>0.05). There was no signifıcant change in leptin levels in response to acute glucose administration in all groups(p>0.05).There was positive correlation between leptin levels and BMI in all groups, while negative correlation was observed with ISI.