AIM: This study aims to evaluate the effect of dipeptidyl peptidase-4 inhibitors on lipid metabolism in patients with type 2 diabetes mellitus (T2D). METHODS: This is a multicenter, open-labeled, randomized controlled study. T2D patients with HbA1c 6.9-8.9% (52-74 mmol/mol) who were under treatment with sulfonylurea were randomly allocated to either the sitagliptin group or the non-sitagliptin group. Glucose and lipid metabolism parameters including apolipoproteins (apo), sterols, and urinary albumin were assessed at baseline, 3, and 6 months of the treatment. RESULTS: A total of 164 patients completed the 6-month observation (n=81 for sitagliptin and n=83 for non-sitagliptin). HbA1c decreased in the sitagliptin group but not in the non-sitagliptin group. Serum TG and total, LDL and HDL cholesterol levels did not change in either group. Apo B-48, apo CII, and apo CIII levels decreased in the sitagliptin group, but not in the non-sitagliptin group. The change in urinary albumin was significantly different between the groups with a preferable change in the sitagliptin group. There were no changes in serum sterols levels in the two groups. CONCLUSIONS: The treatment of sitagliptin for 6 months improves the metabolism of glucose and chylomicron and reduces plasma levels of atherogenic lipoproteins in patients with T2D.