The effect of vildagliptin versus metformin on hepatic steatosis in type 2 diabetic patients: a randomized controlled trial

Background The risk of hepatic steatosis (HS) is elevated in patients with type 2 diabetes mellitus (T2D). Antidiabetic medications may contribute to the prevention or treatment of HS. This study aimed to compare the effects of vildagliptin and metformin on hepatic steatosis in newly diagnosed T2D patients, using the Hepatic Steatosis Index (HSI) and ultrasound grading. Methods The study included 246 newly diagnosed T2D patients who were randomly assigned to two groups. The first group (117 patients) received 50 mg of vildagliptin orally twice daily. The second group (129 patients) received 500 mg of metformin orally twice daily with meals, and the dosage could be gradually increased by 500 mg per week, up to a maximum daily dose of 2000 mg. Baseline and 6-month follow-up assessments included fasting blood glucose (FBG), HbA1c, weight, body mass index (BMI), waist circumference (WC), hip circumference (HC), the Hepatic Steatosis Index (HSI), and hepatic steatosis grading via ultrasound. Results Both groups showed significant improvements in FBG, HbA1c, weight, BMI, WC, HC, HSI, and ultrasound grading of hepatic steatosis from baseline to the 6-month follow-up (p < 0.001). The metformin group demonstrated significantly greater reductions in weight and BMI compared to the vildagliptin group (p = 0.001 and p = 0.009, respectively). However, there was no significant difference between the two groups in terms of hepatic steatosis improvement on ultrasound. Correlation analysis revealed that HSI was significantly associated with HbA1c, BMI, WC, and HC (p < 0.001 for all), as well as FBG (p = 0.008), but not with age. The lipid profile, particularly total cholesterol and LDL, was identified as a stronger predictor of hepatic steatosis, based on high AUC, sensitivity, and specificity values. Conclusion Both vildagliptin and metformin are effective in improving glycemic control in newly diagnosed T2D patients, as evidenced by reductions in FBG and HbA1c levels. Additionally, both drugs significantly reduced the HSI, body weight, and BMI, with metformin showing a more pronounced effect on weight and BMI. Both vildagliptin and metformin effectively decreased hepatic steatosis in T2D patients. Total cholesterol and LDL are important predictors of hepatic steatosis.