This study evaluated the relation of leptin with glycaemic control and the effect of 14 days of diet, or diet combined with gliclazide, glipizide-GITS or metformin treatment, on leptin concentration in 51 female patients with type 2 diabetes mellitus. Leptin levels were similar both at baseline and after treatment in diabetic and control groups. Diabetic patients with basal fasting plasma glucose (FPG) < 10 mmol/l or with basal postprandial plasma glucose (PPPG) < 13.9 mmol/l had significantly higher leptin levels than diabetic patients with basal FPG > or = 10 mmol/l or with basal PPPG > or = 13.9 mmol/l (19.6+/-8.7 vs. 13.65+/-5.4 microg/l, p < 0.05; and 20.2+/-7.9 vs. 12.9+/-5.2 microg/l, p < 0.05, respectively). Mode of treatment did not influence leptin levels. Delta leptin showed a weak correlation with basal FPG (r = 0.346; p < 0.05), basal and post-treatment PPPG (r = 0.335, p < 0.05 and r = 0.325, p < 0.05, respectively) and a moderate correlation with post-treatment FPG (r = 0.391, p < 0.01). In conclusion, leptin level is not affected by the presence of type 2 diabetes mellitus and by short-term treatment with diet or oral antidiabetic drugs but is directly related to glycaemic control in female patients with type 2 diabetes mellitus.