Sodium–glucose cotransporter 2 (SGLT2) inhibitors improve glycaemia in patients with type 2 diabetes by enhancing urinary glucose excretion. We compared the efficacy and safety of canagliflozin, an SGLT2 inhibitor, with glimepiride in patients with type 2 diabetes inadequately controlled with metformin.

We undertook this 52 week, randomised, double-blind, active-controlled, phase 3 non-inferiority trial at 157 centres in 19 countries between Aug 28, 2009, and Dec 21, 2011. Patients aged 18–80 years with type 2 diabetes and glycated haemoglobin A_1c (HbA_1c) of 7·0–9·5% on stable metformin were randomly assigned (1:1:1) by computer-generated random sequence via an interactive voice or web response system to receive canagliflozin 100 mg or 300 mg, or glimepiride (up-titrated to 6 mg or 8 mg per day) orally once daily. Patients, study investigators, and local sponsor personnel were masked to treatment. The primary endpoint was change in HbA_1c from baseline to week 52, with a non-inferiority margin of 0·3% for the comparison of each canagliflozin dose with glimepiride. If non-inferiority was shown, we assessed superiority on the basis of an upper bound of the 95% CI for the difference of each canagliflozin dose versus glimepiride of less than 0·0%. Analysis was done in a modified intention-to-treat population, including all randomised patients who received at least one dose of study drug. This study is registered with ClinicalTrials.gov, number NCT00968812.

1450 of 1452 randomised patients received at least one dose of glimepiride (n=482), canagliflozin 100 mg (n=483), or canagliflozin 300 mg (n=485). For lowering of HbA_1c at 52 weeks, canagliflozin 100 mg was non-inferior to glimepiride (least-squares mean difference −0·01% [95% CI −0·11 to 0·09]), and canagliflozin 300 mg was superior to glimepiride (–0·12% [–0·22 to −0·02]). 39 (8%) patients had serious adverse events in the glimepiride group versus 24 (5%) in the canagliflozin 100 mg group and 26 (5%) in the 300 mg group. In the canagliflozin 100 mg and 300 mg groups versus the glimepiride group, we recorded a greater number of genital mycotic infections (women: 26 [11%] and 34 [14%] vs five [2%]; men: 17 [7%] and 20 [8%] vs three [1%]), urinary tract infections (31 [6%] for both canagliflozin doses vs 22 [5%]), and osmotic diuresis-related events (pollakiuria: 12 [3%] for both doses vs one [<1%]; polyuria: four [<1%] for both doses vs two [<1%]).

Canagliflozin provides greater HbA_1c reduction than does glimepiride, and is well tolerated in patients with type 2 diabetes receiving metformin. These findings support the use of canagliflozin as a viable treatment option for patients who do not achieve sufficient glycaemic control with metformin therapy.

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