Metformin is the recommended first-line pharmacotherapy for patients with type 2 diabetes. There is no consensus on the optimum second-line pharmacotherapy. We compared the efficacy and safety of the sodium glucose cotransporter 2 inhibitor empagliflozin and the sulfonylurea glimepiride as add-on to metformin in patients with type 2 diabetes.

In this double-blind phase 3 trial, patients (aged ≥18 years) with type 2 diabetes and HbA_1c concentrations of 7–10%, despite metformin treatment and diet and exercise counselling, were randomly assigned in a 1:1 ratio with a computer-generated random sequence, stratified by HbA_1c, estimated glomerular filtration rate (eGFR), and region, to empagliflozin (25 mg once daily, orally) or glimepiride (1–4 mg once daily, orally) as add-on to metformin for 104 weeks. Patients and investigators were masked to treatment assignment. The primary endpoint was change from baseline in HbA_1c levels at weeks 52 and 104. Differences in the primary endpoint were first tested for non-inferiority (based on a margin of 0·3%). If non-inferiority was shown, differences in the primary endpoint at week 104 were then tested for superiority. Analysis was done on the full-analysis set—ie, patients who were treated with at least one dose of study drug and had a baseline HbA_1c value. This study is registered with ClinicalTrials.gov, number NCT01167881. A 104-week extension is ongoing.

Between August, 2010, and June, 2011, 1549 patients were randomly assigned to receive empagliflozin (n=769) or glimepiride (n=780); four patients in the empagliflozin group did not receive the assigned treatment. Empagliflozin was non-inferior to glimepiride at both timepoints. At week 104, adjusted mean difference in change from baseline in HbA_1c with empagliflozin versus glimepiride was −0·11% (95% CI −0·19 to −0·02; p=0·0153 for superiority). Adverse events were reported in 661 (86%) patients treated with empagliflozin and 673 (86%) patients treated with glimepiride. Severe adverse events were reported in 72 (9%) patients in the empagliflozin group and 68 (9%) in the glimepiride group. Serious adverse events were reported in 119 (16%) patients in the empagliflozin group and 89 (11%) in the glimepiride group. Confirmed hypoglycaemic adverse events (plasma glucose ≤3·9 mmol/L or requiring assistance) at week 104 were reported in 19 (2%) patients treated with empagliflozin and 189 (24%) patients treated with glimepiride.

Empagliflozin might be an effective and a well tolerated second-line treatment option for patients with type 2 diabetes who have not achieved good glycaemic control on metformin.

Boehringer Ingelheim and Eli Lilly.