Aims: To investigate the efficacy and safety of fast-acting insulin aspart (faster aspart) compared with insulin aspart (IAsp) in participants with type 2 diabetes (T2D) across different subgroups. Methods: We report on a post hoc analysis of onset 9, a 16-week trial of participants with T2D randomised to faster aspart (n = 546) or IAsp (n = 545). Participants were grouped by baseline HbA1c (\ 7.0%, C 7.0%), meal test bolus insulin dose (B 10 units [U], [ 10 U to B 20 U, [ 20 U), body mass index (\ 30 kg/m 2 , C 30 to \ 35 kg/m 2 , C 35 kg/m 2 ), and age (\ 65 years, C 65 years). Outcomes assessed were change from baseline in HbA1c and in 1-h postprandial glucose (PPG) increment, and severe or blood glucose (BG)-confirmed hypoglycaemia.Results: Faster aspart provided reductions in HbA1c comparable to IAsp across all subgroups, with improved 1-h PPG control compared with IAsp in several subgroups. Faster aspart had comparable or improved rates of severe or BGconfirmed hypoglycaemia versus IAsp, particularly in participants with good glycaemic control (HbA1c \ 7.0%), the elderly (C 65 years old), and those with insulin resistance ([ 20 U meal test bolus insulin dose). Conclusions: Faster aspart provides effective overall glycaemic control, with improved early PPG control compared with IAsp across a range of patient characteristics. Clinical Trial Registration: NCT03268005.