GLP-1 receptor agonists are an established therapy in patients with type 2 diabetes; however, their role in type 1 diabetes remains to be determined.Determine efficacy and safety of once-weekly albiglutide 30mg (up-titration to 50mg at week 6) versus placebo together with insulin in patients with new-onset type 1 diabetes and residual insulin production.52-week, randomized, phase 2 study (NCT02284009).A prespecified Bayesian approach, incorporating placebo data from a prior study, allowed for 3:1 (albiglutide:placebo) randomization. The primary endpoint was 52-week change from baseline in mixed meal tolerance test (MMTT) stimulated 2-hour plasma C-peptide area under the curve (AUC). Secondary endpoints included metabolic measures and pharmacokinetics of albiglutide.12/17 (70.6%, placebo) and 40/50 (80.0%, albiglutide) patients completed the study. Within our study, mean (SD) change from baseline to week 52 in MMTT-stimulated 2-hour plasma C-peptide AUC was -0.16 nmol/L (0.366) with placebo and -0.13 nmol/L (0.244) with albiglutide. For the primary Bayesian analysis (including prior study data) the posterior treatment difference (95% credible interval) was estimated at 0.12 nmol/L (0-0.24);the probability of a difference =0.2 nmol/L between treatments was low (0.097). A transient significant difference in maximum C-peptide was seen at week 28. Otherwise, no significant secondary endpoint differences were noted. . On-therapy adverse events were reported in 82.0% (albiglutide) and 76.5% (placebo) of patients.In newly diagnosed patients with type 1 diabetes, albiglutide 30‒50 mg weekly for 1 year had no appreciable effect on preserving residual β-cell function versus placebo.