Association of leptin with type 2 diabetes in non-obese subjects.

BACKGROUND South Asians have a high tendency to develop type 2 diabetes even at low BMI. We evaluated serum leptin levels in a group of non-obese type 2 diabetics. METHODS An observational study conducted on 90 subjects, 55 with Type 2 diabetes mellitus, and 35 normal controls (non-diabetics). BMI, waist circumference, serum leptin, and serum glucose were measured. The correlation between these variables was studied by multiple regression analysis. RESULTS Serum leptin levels were positively correlated with BMI in obese (r = 0.976) and non-obese diabetics (r = 0.956). Serum leptin was related with diabetes (r = -0.153, p = 0.001). Serum leptin was highly correlated with waist circumference in obese than non-obese diabetics, (r = 0.753). Mean serum leptin level was 21.4 etag/ml in non-obese diabetics and 34.9 etag/ml in diabetic group. It is even lower than the non-obese, non-diabetics (23.3 etag/ml). Multivariate linear regression analysis between leptin and age, weight, BMI, waist circumference in patients shows only a strong association with BMI in diabetics (p = 0.0001), while in non-diabetic it was not significant (p = 0.07). Serum leptin was high in diabetics taking oral hypoglycaemic (37.8 +/- 19.1 etag/ml), while it was low in diabetics taking insulin injections (29.3 +/- 24.2 etag/ml). CONCLUSION Low leptin levels are associated with type 2 diabetes mellitus independent of changes in BMI.