Dipeptidyl peptidase-4 inhibitors (DPP-4I), key regulators of the actions of incretin hormones, exert anti-hyperglycemic effects in type 2 diabetes mellitus (T2DM) patients. A major unanswered question concerns the potential ability of DPP-4I to improve intrahepatic lipid (IHL) content in nonalcoholic fatty liver disease (NAFLD) patients. The aim of this study was to evaluate the effects of sitagliptin on IHL in NAFLD patients.

A prospective, 24-week, single-center, open-label, comparative study enrolled 68 Chinese NAFLD patients with T2DM. Subjects were randomly divided into 4 groups: control group who did not take medicine (14 patients); sitagliptin group who received sitagliptin treatment (100mg per day) (17 patients); metformin group who received metformin (500mg three times per day) (17 patients); and sitagliptin plus metformin group who received sitagliptin (100mg per day) and metformin (500 mg three times per day) (20 patients). IHL, physical examination (waist circumstances, WC; body mass index, BMI), glucose-lipid metabolism (fasting plasma glucose, FPG; hemoglobin A1c, Hb1A1c; triglycerides; cholesterol; alanine aminotransferase, ALT; aspartate aminotransferase, AST) were measured at baseline and at 24 weeks.

Inclusion Criteria:

• age 30-70 years old
• fulfillment of the diagnostic criteria for T2DM by WHO in 1999 (HbA1c ranged from 7% to 10%, FPG < 11 mol/l, 2-hour blood glucose postprandial < 20mmol/l)
• Fulfillment of the diagnostic criteria for NAFLD according to the guidelines of the Chinese Medical Association in 2010. The IHL content was measured by using 1H-magnetic resonance spectroscopy (1H-MRS) quantitative detection, and the liver fat content of the enrolled subjects was more than 5.5%. The subjects included in this study had either no history of alcohol consumption or their alcohol intake was less than 70 g/week in males and less than 140 g/week in females. Liver transaminase and serum creatinine were less than two times the upper limit of normal

Exclusion Criteria:

• T2DM complicated with ketoacidosis, hyperosmolarity, acute and chronic infection ● serious heart, liver, kidney, lung disease, and liver damage
• alcoholic fatty liver
• drug use that influences glucose metabolism such as thiazide diuretics and hormones within three months
• Hypertension ≥ 180/110 mmHg
• gastrointestinal disease or absorption dysfunction
• recent trauma, surgery, or other conditions resulting in an increased stress response within the past three months.