Liraglutide, a glucagon-like peptide 1 (GLP-1) agonist and antidiabetic drug, has shown neuroprotective effects in animal models. In this study, we aimed to evaluate the safety and efficacy of liraglutide in mild to moderate Alzheimer's disease syndrome. 'Evaluating liraglutide in Alzheimer's disease' (ELAD) is a multicenter, randomized, double-blind, placebo-controlled phase 2b trial in 204 participants with mild to moderate Alzheimer's disease syndrome with no diabetes. Participants received daily injections of liraglutide or placebo for 52 weeks. They underwent fluorodeoxyglucose positron emission tomography, magnetic resonance imaging and detailed neuropsychometric evaluations. The primary outcome was a change in cerebral glucose metabolic rate. Secondary outcomes were safety and tolerability and cognitive changes. The primary outcome showed no significant differences in cerebral glucose metabolism (difference = -0.17; 95% confidence interval: -0.39 to 0.06; P = 0.14) between the two groups. The secondary outcome-score on the Alzheimer's Disease Assessment Scale-Executive domain (ADAS-Exec)-performed better in liraglutide-treated patients compared to placebo (0.15; 95% confidence interval: 0.03-0.28; unadjusted P = 0.01). No significant differences were observed in Alzheimer's Disease Cooperative Study-Activities of Daily Living (ADCS-ADL) (-0.58; 95% confidence interval: -3.13 to 1.97; unadjusted P = 0.65) or Clinical Dementia Rating-Sum of Boxes (CDR-SoB) (-0.06; 95% confidence interval: -0.57 to 0.44; unadjusted P = 0.81) scores. Liraglutide was generally safe and well tolerated in non-diabetic patients with Alzheimer's disease. ClinicalTrials.gov identifier: NCT01843075 .