To examine the association of baseline patient characteristics with study outcomes in people with type 2 diabetes receiving insulin glargine 300 U/mL (Gla-300) versus glargine 100 U/mL (Gla-100), over a 6-month period. A post hoc patient-level meta-analysis using data from three multicenter, randomized, open-label, parallel-group, phase 3a studies of similar design, in people previously receiving either basal and prandial insulin, basal insulin + oral antihyperglycemic drugs, or no prior insulin (EDITION 1, 2 and 3, respectively). The endpoints, glycated hemoglobin (HbA(1c)), hypoglycemia, body weight change, and insulin dose were investigated by subgroups: age (< 65 and 65 years), body mass index (BMI; < 30 and 30 kg/m(2)), age at onset (< 40, 40-50, and > 50 years), and diabetes duration (< 10 and 10 years). Reduction in HbA(1c) was comparable between insulins, regardless of subgroup. The lower risk of 1 nocturnal (00:00-05:59 h) confirmed ( 3.9 mmol/L [ 70 mg/dL]) or severe hypoglycemic event with Gla-300 versus Gla-100 was also unaffected by participant characteristics. While heterogeneity of treatment effect between diabetes duration subgroups was seen for the risk of 1 confirmed ( 3.9 mmol/L [ 70 mg/dL]) or severe hypoglycemic event at any time (24 h), treatment effect consistently favored Gla-300; no evidence of heterogeneity was observed for the other subgroups. Annualized rates of confirmed ( 3.9 mmol/L [ 70 mg/dL]) or severe hypoglycemia and body weight change were not influenced by participant characteristics; a similar pattern was observed with insulin dose. Comparable glycemic control was observed with Gla-300 versus Gla-100, with less hypoglycemia, regardless of age, BMI, age at onset or diabetes duration. Sanofi. Plain language summary available for this article.