A Meta-Analysis of Placebo-Controlled Clinical Trials Assessing the Efficacy and Safety of Incretin-Based Medications in Patients with Type 2 Diabetes

Aims: A systematic review of the literature, in combination with a meta-analysis of randomized controlled trials comparing treatments with placebo, was conducted to provide an update on the clinical efficacy and safety of incretin-based medications in adult patients with type 2 diabetes. Methods: A literature search (2000-2009) identified 38 placebo- controlled trials (phase II or later - parallel design) comparing exenatide (n = 8), liraglutide (n = 7), vildagliptin (n = 11) and sitagliptin (n = 12) with placebo. Outcomes were change from baseline in HbA(1c) and in weight, and the number of patient-reported hypoglycemic episodes. HbA(1c) and weight outcomes were analyzed as weighted mean differences (WMD), and the number of hypoglycemic episodes as relative risks (RR). Results: Patients receiving liraglutide showed greater reduction in HbA(1c) in comparison to placebo (WMD = -1.03, 95% confidence interval, CI = -1.16 to -0.90, p < 0.001) than those on sitagliptin (WMD = -0.79, 95% CI = -0.93 to -0.65, p < 0.001), exenatide (WMD = -0.75, 95% CI = -0.83 to -0.67, p < 0.001) or vildagliptin (WMD = -0.67, 95% CI = -0.83 to -0.52, p < 0.001). Weight was statistically significantly negatively associated with exenatide (WMD = -1.10, 95% CI = -1.32 to -0.87, p < 0.001) and positively associated with sitagliptin (WMD = 0.60, 95% CI = 0.33-0.87, p < 0.001) and vildagliptin (WMD = 0.56, 95% CI = 0.27-0.84, p < 0.001). The number of patient-reported hypoglycemic episodes was statistically significantly associated with the use of sitagliptin (RR = 2.56, 95% CI = 1.23-5.33, p = 0.01) and exenatide (RR = 2.40, 95% CI = 1.30-4.11, p = 0.002). Conclusion: Incretin-based therapies are effective in glycemic control and also offer other advantages such as weight loss (exenatide and liraglutide). This may have an important impact on patient adherence to medication. Copyright (C) 2010 S. Karger AG, Basel