Effect of GLP-1 receptor agonists on waist circumference among type 2 diabetes patients: a systematic review and network meta-analysis

Glucagon-like peptide-1 receptor agonists (GLP-1RAs) are increasingly used in patients with type 2 diabetes. However, the effect on abdominal obesity has not yet been confirmed. The study aimed to systematically evaluate the effect of GLP-1RAs on waist circumference in patients with type 2 diabetes. MEDLINE, EMBASE, the Cochrane library and www.clinicaltrialgov were searched through October 31, 2013. Randomized controlled trials with available data were selected if they compared GLP-1 RAs with placebo and traditional anti-diabetic drugs with a duration ≥8 weeks. Weighted mean difference was estimated using random-effect model. Network meta-analysis was performed to supplement direct comparisons. Seventeen trials with 12 treatments were included. Overall, significant reductions on waist circumference following treatment of liraglutide—1.8 mg once daily (−5.24 cm, 95 % CI −7.68, −2.93), liraglutide—1.2 mg once daily (−4.73 cm, 95 % CI −6.68, −2.65) and exenatide—10 μg twice daily (−1.34 cm, 95 % CI −2.00, −0.75) were detected versus placebo. The reduction effect was more evident when compared with insulin and thiazolidinediones (range −1.71 to −8.03 cm). Compared with exenatide, liraglutide—0.6 mg once daily, taspoglutide, liraglutide—1.2 mg once daily and liraglutide—1.8 mg once daily significantly decreased waist circumference from −3.32 to −6.01 cm. Besides, liraglutide—1.8 mg once daily significantly decreased waist circumference by −1.73 cm (95 % CI −3.04, −0.55) versus sitagliptin, whereas no significant difference following liraglutide—1.2-mg-once-daily treatment was detected compared with liraglutide—1.8 mg once daily and sitagliptin. Reduction was observed with statistical significance for exenatide—10 μg twice daily compared with exenatide—5 μg twice daily (−1.21 cm, 95 % CI −2.43, −0.06). Ranking probability analysis indicated liraglutide—1.8 mg once daily and liraglutide—1.2 mg once daily decreased waist circumference most among all 12 treatments with probability of 98.36% and 91.82 %, respectively. Some GLP-1RAs, especially liraglutide—1.8 mg once daily and liraglutide—1.2 mg once daily, were associated with a significant reduction in waist circumference.