The study evaluated the efficacy and tolerability of the dipeptidyl peptidase-4 inhibitor, vildagliptin, and metformin in drug-naïve elderly patients with type 2 diabetes. The primary objective was to demonstrate non-inferiority of vildagliptin vs. metformin in glycated haemoglobin (HbA₁c) reduction. This was a double-blind, randomized, multicentre, active-controlled, parallel-group study of 24-week treatment with vildagliptin (100 mg daily, n = 169) or metformin (titrated to 1500 mg daily, n = 166) in drug-naïve patients with type 2 diabetes aged greater-than-or-equal65 years (baseline HbA₁c 7-9%). Participants had a mean age of 71 years, known duration of diabetes of 3 years and mean baseline HbA₁c of 7.7%. At end-point, vildagliptin was as effective as metformin, improving HbA₁c by -0.64 ± 0.07% and -0.75 ± 0.07%, respectively, meeting the predefined statistical criterion for non-inferiority (upper limit of 95% confidence interval for between-treatment difference less-than or equal to0.3%). Body weight changes were -0.45 ± 0.20 kg in vildagliptin-treated patients (p = 0.02) and -1.25 ± 0.19 kg in metformin-treated patients (p < 0.001; p = 0.004 vs. vildagliptin). The proportion of patients experiencing an adverse event (AE) was 44.3 vs. 50.3% in patients receiving vildagliptin and metformin respectively. Gastrointestinal (GI) AEs were significantly more frequent with metformin (24.8%) than with vildagliptin (15.0%, p = 0.028), mainly driven by a 4.4-fold higher incidence of diarrhoea. A low incidence of hypoglycaemia was observed in both treatment groups (0% with vildagliptin and 1.2% with metformin). Vildagliptin is an effective and well-tolerated treatment option in elderly patients with type 2 diabetes, demonstrating similar improvement in glycaemic control as metformin, with superior GI tolerability.