INS and chronic obstructive pulmonary disease: Subgroup analysis of T2DM and exacerbated COPD revealed that metformin users compared with nonusers had lower risk of all-cause mortality in female patients, those ≥65 years of age, CCI = 1 and ≥2, DCSI of 1 and ≥2, >2 OADs, and with insulin therapy.