Comparison of Serum Leptin levels of Non-Diabetic and Diabetic Obese Subjects and its Relationship to Anthropometric Indices

Leptin, the product of the ob gene, plays a significant role in the pathogenesis of obesity and type 2 diabetes mellitus. The aim of this study was to compare serum leptin level in non-diabetic and type 2 diabetic obese subjects and assess its relationship to anthropometric indices. This cross-sectional study was performed on 35 obese subjects with type 2 diabetes and 35 non-obese, non-diabetics. Fasting lipid profiles were measured using enzymatic methods. The NycoCard HbA1c Kit was used to measure HbA1c. Serum leptin, insulin and glucose levels were measured by an enzyme immunoassay, using a commercially available kit and glucose oxidase methods respectively. The insulin resistance index was calculated by homeostasis model assessment (HOMA-IR). The mean of insulin resistance index (HOMA-IR), HbA1c, diastolic blood pressure, triglyceride and fasting glucose in diabetics were significantly higher than in non-diabetic subjects (P < 0.05). Serum leptin levels were significantly lower in diabetics than in non-diabetics (21.51±2.18 vs. 30.36±2.46) and were significantly higher in women than in men (31.85±17.96 vs.12.80±9.02) in the diabetic and (36.11±10.99 vs. 23.55±15.72) in non-diabetic groups. There was a direct and significant correlation between serum leptin levels with hip circumference (r= 0.450, p= 0.04) in diabetics and (r=0.590, p=0.000) in non-diabetics, and between leptin and BMI (r= 0.666, p= 0.000) in diabetic and (r= 0.490, p= 0.003) in non-diabetic groups. Since the mean serum leptin level is lower in obese diabetes, compared to non-diabetics, further studies are required to clarify the mechanisms of lower leptin levels in obese diabetic subjects.