INS and diabetes mellitus: All-cause mortality rate per 10 person-years of HF patients with DM were 1.45 (95% CI 1.29–1.61), 2.18 (95% CI 1.98–2.39), and 1.98 (95% CI 1.84–2.13) in the OHA alone, insulin alone, and combination of insulin and OHAs group, respectively (Additional file 1: Table S3).