Higher mortality rate in patients with heart failure who are taking commonly prescribed antidiabetic medications and achieve recommended levels of glycaemic control.

Current guidelines for diabetes recommend that physicians attain a glycated haemoglobin (HbA1c) concentration ≤7.0%, but this target may not be applicable to those with heart failure. Fourteen studies in patients with chronic heart failure that examined the relationship between the level of HbA1c and risk of death specified whether HbA1c was influenced by treatment with antidiabetic medications. In patients with heart failure not receiving glucose-lowering drugs, the mortality rate was not higher among those with an HbA1c concentration <7.0%. By contrast, in patients who were treated with insulin, sulphonylureas and thiazolidinediones, an inverse or U-shaped relationship between HbA1c and the risk of death was generally observed, and mortality was lowest in patients with both heart failure and diabetes if the level of HbA1c was >7.0%. These studies suggest that patients with both heart failure and diabetes are at increased risk of death if they are prescribed certain glucose-lowering drugs to achieve levels of HbA1c <7.0%.