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Invited Commentary
March 14, 2011

Diabetes and Cardiovascular Risk Equivalency: Do Age at Diagnosis and Disease Duration Affect Risk Stratification?Comment on “Impact of Diabetes on Cardiovascular Disease Risk and All-Cause Mortality in Older Men”

Arch Intern Med. 2011;171(5):410-411. doi:10.1001/archinternmed.2010.524

The term CHD risk equivalence for individuals with diabetes has become popular and controversial following the report by Haffner et al1 more than a decade ago of higher rates of cardiac events in persons with diabetes. For individuals in this category, the updated version of the National Cholesterol Education Adult Treatment Panel III advocates a target reduction of low-density lipoprotein cholesterol levels to less than 100 mg/dL (to convert to millimoles per liter, multiply by 0.0259) despite the lack of evidence to support this target value. Given the rising prevalence of diabetes and related atherosclerotic events since the publication of the widely cited study, the enthusiasm for this concept is further driven by the availabilities of lipid-lowering therapies (mainly statins), which lower rates of CHD events among individuals with high-risk profiles. Thus, basing target lipid levels on readily ascertained characteristics such as the presence or absence of diabetes appears practicable. However, this needs to be balanced against the potential harms and significant resource implications of advocating blanket treatment targets to all patients on the basis of a diagnosis of diabetes. In our enthusiasm to extrapolate the findings from Haffner et al1 to a host of population groups, we have somehow overlooked some of the study's important limitations, namely, the lack of power to detect differences between the 2 groups of patients being studied. Furthermore, the study was restricted to self-selected Finnish patient groups aged 45 to 64 years. The significant heterogeneity to the risk of developing CHD in patients with diabetes was further evident by the observation from the Detection of Ischemia in Asymptomatic Diabetics (DIAD) Study.2 When targeting a “healthier” population of asymptomatic patients with diabetes, the observed annual cardiac event rate in this study was very low at 0.69%. In the Strong Heart Study, which included communities with high risk of developing diabetes and CHD, the rates of CHD in patients with diabetes appear to depend in part on coexisting risk factors,3 and only those with multiple risk factors had rates of CHD events equivalent to those of patients with established CHD. Not surprisingly, subsequent large observational studies from different population groups have provided contradictory findings, with some supporting diabetes as a CHD risk equivalence4 and others not.5,6