AimsIndividuals with both diabetes mellitus (DM) and atherosclerotic cardiovascular disease (ASCVD) are at very high risk of cardiovascular events. This post‐hoc analysis evaluated efficacy and safety of the PCSK9 inhibitor alirocumab among 984 individuals with DM and ASCVD pooled from 9 ODYSSEY Phase 3 trials.Materials and methodsChanges in low‐density lipoprotein cholesterol (LDL‐C) and other lipids from baseline to Week 24 were analysed (intention‐to‐treat) in four pools by alirocumab dosage (150 mg every 2 weeks [150] or 75 mg with possible increase to 150 mg every 2 weeks [75/150]), control (placebo/ezetimibe) and background statin usage (yes/no).ResultsAt Week 24, LDL‐C changes from baseline in pools with background statins were −61.5% with alirocumab 150 (vs −1.0% with placebo), −46.4% with alirocumab 75/150 (vs +6.3% with placebo) and −48.7% with alirocumab 75/150 (vs −20.6% with ezetimibe), and −54.9% with alirocumab 75/150 (vs +4.0% with ezetimibe) without background statins. A greater proportion of alirocumab recipients achieved LDL‐C < 70 and < 55 mg/dL at Week 24 vs controls. Alirocumab also resulted in significant reductions in non‐high‐density lipoprotein cholesterol, apolipoprotein B and lipoprotein(a) vs controls. Alirocumab did not appear to affect glycaemia over 78‐104 weeks. Overall safety was similar between treatment groups, with a higher injection‐site reaction frequency (mostly mild) with alirocumab.ConclusionAlirocumab significantly reduced LDL‐C and other atherogenic lipid parameters, and was generally well tolerated in individuals with DM and ASCVD.