In May this year, we published an article on ▼Liraglutide for type 2 diabetes (DTB 2010; 48: 50–3). At the time, there were no published randomised controlled trials comparing liraglutide with ▼sitagliptin. However, since then, there has been publication of a 26-week non-blinded randomised trial that compared subcutaneous liraglutide 1.2mg and 1.8mg daily with oral sitagliptin 100mg daily, all in addition to metformin, in 665 patients with type 2 diabetes and inadequate glycaemic control (HbA_1c 7.5–10.0%) despite treatment with metformin (at least 1,500mg daily) for 3 months or longer.1

At 26 weeks, in this study, the mean change in HbA_1c levels (the primary outcome measure) from a baseline of around 8.5% was greater with both doses of liraglutide than with sitagliptin (1.2mg: −1.24%, 95% CI −1.37 to −1.11; 1.8mg: −1.50%, 95% CI −1.63 to −1.37; sitagliptin −0.90%, 95% CI −1.03 to −0.77). In terms of secondary outcome measures, mean weight loss was greater with both doses of liraglutide than with sitagliptin (1.2mg: −2.86kg, 95% CI −3.39 to −2.32; 1.8mg: −3.38kg, 95% CI −3.91 to −2.84; sitagliptin: −0.96kg, 95% CI −1.50 to −0.42), but neither drug reduced systolic blood pressure significantly. More patients developed adverse events with liraglutide (66% with 1.2mg and 73% with 1.8mg) than with sitagliptin (58%), the most common being gastrointestinal symptoms, particularly nausea that diminished over time.

The results of this study show that liraglutide reduces HbA_1c levels more than sitagliptin, but do not affect the conclusion of DTB’s review on liraglutide for type 2 diabetes. This stated that “liraglutide is expensive and currently lacks long-term safety data. Therefore, we believe that it should be considered only after conventional oral hypoglycaemic therapy (including a glitazone) has failed, and where the avoidance of weight gain is crucial, insulin therapy is contraindicated, or the individual is unable to tolerate exenatide.”