The prevalence of heart failure (HF) among the adult population is estimated at 1–2%, but there are reports as high as 10%, paralleling this scenario is a rapid rise in diabetes globally, with an estimated increase from 8.5% in 2011 to 9.8% in 2030. Cardiovascular complications are frequent in type 2 diabetes (T2D), making this disease an important risk factor for subsequent HF, and, in addition, poor glucose control measured as glycated hemoglobin (HbA1c) predicts future development of HF. The cardiac complications secondary to diabetes include secondary to coronary artery disease (CAD), diabetic cardiomyopathy, and sudden cardiac death (SCD). The most meaningful clinical endpoints for prognosis in patients with HF are mortality and hospitalization for HF. This chapter covers the interaction between diabetes and left ventricular ejection fraction, diabetic cardiomyopathy, treatment of patients with diabetes and HFrEF, treatment of patients with diabetes and HFpEF, and treatment of diabetes in patients with heart failure.