Potential pathogenic factors contribut- ing to cardiac dysfunction in patients with diabetes mellitus include the direct and indirect effects of hy- perglycemia and advanced glycation end products, autonomic dysfunction, microangiopathy, subclinical macrovessel (coronary) disease, mitochondrial dysfunction, lipotoxicity, and potential Association of Diabetes Mellitus With Outcomes in Patients With Established HF Diabetes mellitus is commonly present in patients with HF. It is estimated that 12% to 30% of patients with symptomatic HF have previously diagnosed diabetes Between 1995 and 1999 in Olmsted County, Minnesota, the prevalence of diabetes mellitus in pa- tients with incident HF was 25%.106 The prevalence of diabetes mellitus appears to be even greater in patients hospitalized with acute decompensated HF, with regis- tries demonstrating a prevalence of 40% to 44%.107,108 Similarly, in a registry of individuals with HFpEF, diabetes mellitus was present in 46% of patients.109 Systematic assessment with oral glucose tolerance testing in pa- tients with HF without a previous diagnosis of diabetes mellitus may also identify a large proportion (18%) of patients with newly diagnosed diabetes mellitus.110 The presence of diabetes mellitus in patients with HF is associated with increased morbidity and mortal- In the CHARM Program (Candesartan Heart Failure Assessment of Reduction), rates of HF hospitaliza- tion in patients with diabetes mellitus were approximately twice the rates of those without diabetes mellitus.113 In SOLVD (Studies of Left Ventricular Dysfunction), the ad- justed relative risk of HF hospitalization for subjects with in the treatment and prevention trials, respectively.116 The association of increased mortality with diabetes mel- litus in patients with HF appears to be limited to or more apparent in patients with an ischemic than in those with a nonischemic pathogenesis.112,117 Diabetes mellitus has also been independently associated with increased mor- tality in patients with HF in multiple observational studies and clinical trials.104,106,111,113,114 Treatment: Current Evidence of HF Risk Reduction With the Treatment of Diabetes Mellitus in Patients With HF Given the increased morbidity and mortality associated with diabetes mellitus and HF, efforts for preventing HF are increasingly important. 