We conducted a multicentre, randomized phase 3 trial in China to evaluate the efficacy and safety of cofrogliptin (HSK7653), a novel long-acting dipeptidyl peptidase-4 inhibitor, in patients with drug-naïve type 2 diabetes (T2D). Patients with inadequately controlled T2D were randomly assigned (1:1:1) to cofrogliptin 10 mg, cofrogliptin 25 mg or placebo, taken orally once every 2 weeks for a 24-week double-blind period. Eligible patients then received cofrogliptin 25 mg in a 28-week open-label extension. The primary endpoint was the change in glycated haemoglobin (HbA1c) from baseline to week 24. In total, 475 patients (median age: 54.0 years) were randomized and received at least one dose of cofrogliptin 10 mg (n = 158), cofrogliptin 25 mg (n = 158) or placebo (n = 159); 401 patients entered the open-label extension. At week 24, the least-squares (LS) mean difference (95% confidence interval [CI]) in HbA1c versus placebo was -0.63% (-0.81, -0.46) with cofrogliptin 10 mg and -0.59% (-0.77, -0.42) with cofrogliptin 25 mg (both p < 0.0001). The LS mean (standard error) change in HbA1c from baseline was maintained at the end of the study in patients given open-label cofrogliptin 25 mg for an additional 28 weeks: cofrogliptin 10 mg: -0.86% (0.07); cofrogliptin 25 mg: -0.74% (0.07); placebo: -0.89% (0.07). Over the entire study, common adverse events were hyperuricaemia, hyperlipidaemia, hypertriglyceridaemia, increased lipase, upper respiratory tract infection and urinary tract infection. Hypoglycaemic events did not significantly differ between groups. Cofrogliptin provided glycaemic control over 52 weeks and was generally well tolerated in patients with T2D. Registered on Clinicaltrials.gov with the registration number NCT04556851 (https://clinicaltrials.gov/study/NCT04556851).