Aim To compare the efficacy and safety of once-weekly dulaglutide with that of insulin glargine in combination with metformin and/or a sulphonylurea in mainly Asian patients with type 2 diabetes mellitus (T2DM). Materials and Methods In this 52-week, randomized, parallel-arm open-label study, we enrolled patients aged >= 18 years with T2DM for at least 6 months and a glycated haemoglobin (HbA1c) concentration >= 53.0 mmol/mol (7.0%) and <= 96.7 mmol/mol (11.0%). The primary outcome was change in HbA1c from baseline to week 26 to determine non-inferiority of dulaglutide 1.5 mg versus glargine. Results A total of 774 patients from China, South Korea, Mexico and Russia were randomly assigned (1:1:1) to dulaglutide 1.5 mg, dulaglutide 0.75 mg or glargine treatment groups. The patients' mean age was 55 years and the average T2DM duration was similar to 8 years. The least squares mean (SE) changes from baseline in HbA1c at 26 weeks were - 18.9 (0.73) mmol/mol (-1.73 [0.067]%) for dulaglutide 1.5 mg and -14.5 (0.73) mmol/mol (-1.33 [0.067]%) for dulaglutide 0.75 mg, compared with -12.7 (0.73) mmol/mol (-1.16 [0.067]%) for glargine. Statistical criteria for superiority were met with both dulaglutide 1.5 mg and dulaglutide 0.75 mg. More patients in the dulaglutide 1.5 and 0.75 mg groups achieved HbA1c target <53.0 mmol/mol (<7.0%) than in the glargine group at week 26 (P < 0.001 and P = 0.004, respectively). Body weight decreased with dulaglutide and increased with glargine. The incidence and rate of total hypoglycaemia were lower with dulaglutide versus glargine. Gastrointestinal adverse events, including diarrhoea and nausea, were the most frequently reported for patients taking dulaglutide. Conclusions Once-weekly dulaglutide provides greater improvement in HbA1c, with weight loss and less hypoglycaemia, than once-daily insulin glargine in a population of mainly Asian patients with T2DM who had failed to achieve optimal glycaemic control on metformin and/or a sulphonylurea.