The Epidemiology of Heart Failure in Diabetes Mellitus
The increased incidence of heart failure in diabetics was first described in the Framingham Heart Study. In the original publication, DM conferred twice the risk in men and nearly five times the risk in women for the development of heart failure.6 Since then the impact of DM on the incidence of heart failure has been repeatedly demonstrated. The incidence of heart failure is 2.5 times higher in diabetics than the general population.7 Diabetes contributes not only to the increased incidence of heart failure, but it is also an independent risk factor for left ventricular hypertrophy, a clearly defined precursor to heart failure.
In the Cardiovascular Health Study, diabetes was shown to be an independent risk factor for the development of heart failure.8 The increased risk for the development of heart failure is magnified in two specific sub-populations. As the diabetic population ages the risk of developing heart failure increases. Demonstrated in a Kaiser Permanente registry the incidence of heart failure doubles in diabetics for every decade above 45 years of age9 and similarly in a study of the elderly (>65 years), 39 % of diabetic patients developed heart failure compared to 23 % of non-diabetics after 3.5 years.10 In a study of 150,000 Medicare patients the incidence of heart failure was 13 % and the prevalence reached 24 %.11 Patients with a history of ischaemic heart disease and diabetes are also at increased risk for the development of heart failure compared to those without an ischaemic burden. Tenebaum A et al. demonstrated that heart failure developed more frequently in DM with ischaemic heart disease compared to those with non-ischaemic heart disease, 46 % vs 36 % respectively. Even the presence of impaired fasting glucose in ischaemic heart disease carried an increased risk of heart failure.12
While the diagnosis of diabetes is an independent risk factor for heart failure, recent data has shown that glycaemic control is an important prognostic marker for heart failure. Glycosylated haemoglobin (HgbA1c) is directly associated with the risk of heart failure. An increase in HgbA1c from 6.5 % to 10.5 % increases the risk of developing heart failure nearly 4-fold.13 The risk of heart failure increases linearly with increasing HgbA1c. For each 1 % increase in HgbA1c the risk of heart failure increase 8–12%.14,15 The risk for the development of heart failure in diabetics may be more closely related to overall long-term glycaemic control and duration of DM, rather than the HgbA1c at an individual point in time.