Aims To investigate the effect of adding the short-acting glucagon-like peptide 1 receptor agonist (GLP-1RA) exenatide to insulin treatment on markers of cardiovascular risk in type 1 diabetes. Materials and methods In a randomized, double-blind, parallel-group trial, 108 individuals with type 1 diabetes aged >= 18 years on multiple daily injection therapy with a body mass index >22.0 kg/m(2)and glycated haemoglobin concentration of 59 to 88 mmol/mol (7.5%-10.0%) were randomized (1:1) to preprandial subcutaneous injection of 10 mu g exenatide (Byetta (R)) or placebo three times daily over 26 weeks as add-on treatment to existing insulin therapy. Reported markers of cardiovascular risk were secondary endpoints and were analyzed in a baseline-adjusted linear mixed model in the intention-to-treat population. The primary results of this study, the MAG1C (Meal-time Administration of exenatide for Glycaemic control in type 1 diabetes Cases) trial, were previously reported. Results Exenatide changed total fat mass by -2.6 kg (95% confidence interval [CI] -3.6; -1.6;P < 0.0001) and lean body mass by -1.1 kg (95% CI -1.9; -0.4;P= 0.01) compared with placebo, as assessed by dual-energy X-ray absorptiometry. Fat mass reductions were similar for central and peripheral fat mass. Exenatide did not change levels of interleukin-2 or -6; tumour necrosis factor-alpha; C-reactive protein; N-terminal prohormone of brain natriuretic peptide; or 8-oxo-7,8-dihydroguanosine (RNA oxidation marker) and 8-oxo-7,8-dihydro-2 '-deoxyguanosine (DNA oxidation marker). Conclusions Exenatide added to insulin therapy in type 1 diabetes for 26 weeks resulted in body weight loss primarily from fat mass reduction, but had no effect on biomarkers of cardiovascular disease risk.