Comparative Efficacy of Sitagliptin Versus Vildagliptin as Add-On to Metformin in Type 2 Diabetes Mellitus — A Randomized Trial

Abstract

Background: DPP-4 inhibitors are widely used second-line agents in T2DM. Head-to-head data comparing sitagliptin and vildagliptin as add-on to metformin in South Asian patients are scarce. Methods: An open-label randomized trial enrolled 120 T2DM patients with HbA1c 7.5 to 10% on metformin monotherapy at a diabetology centre in Sri Lanka, Feb 2023 to March 2024. Patients were randomized 1:1 to sitagliptin 100 mg once daily (n equals 60) or vildagliptin 50 mg twice daily (n equals 60) for 24 weeks. Results: Baseline HbA1c was comparable (8.4 plus or minus 0.8% vs 8.3 plus or minus 0.9%). At 24 weeks, HbA1c reduction was similar: sitagliptin minus 1.12 plus or minus 0.62% versus vildagliptin minus 1.18 plus or minus 0.68% (p equals 0.624). Target HbA1c below 7% was achieved in 38.3% versus 41.7% (p equals 0.716). FPG and PPG reductions were comparable. Both were weight-neutral. Hypoglycaemia was rare (3.3% vs 5.0%, p equals 0.648). Conclusion: Sitagliptin and vildagliptin provide comparable glycaemic efficacy and safety as add-on to metformin in Sri Lankan T2DM patients. Choice may be guided by cost and dosing preference.