How long an elderly person with diabetes mellitus combined with heart failure can live varies widely among individuals and depends on the glycemic control and the state of the elderly person’s body. When the elderly have good glycemic control and undergo regular cardiovascular checkups and treatments, their survival can generally reach the normal life expectancy. Timely cardiovascular protection or surgical treatment after the onset of heart failure to effectively maintain basic cardiac function can also improve the prognosis. However, in older adults with chronically elevated blood glucose and chronic cardiac damage, survival may be relatively shortened if chronic cardiovascular decline occurs without timely pharmacologic or surgical treatment. If an acute cardiovascular attack occurs, sudden death may occur. When a diagnosis of diabetes mellitus combined with heart failure is made, it is important to seek medical attention as soon as possible to take treatment measures.