Impact of Diabetes on Cardiovascular Disease Risk and All-Cause Mortality in Older Men: Influence of Age at Onset, Diabetes Duration, and Established and Novel Risk Factors

Study Questions:

What is the influence of age at onset and duration on the impact of diabetes mellitus on cardiovascular disease risk and all-cause mortality among men ages 60-79 years?

Methods:

This was a prospective study of 4,045 men, ages 60-79 years, followed up for a mean of 9 years. There were 372 major coronary heart disease (CHD) events (fatal and nonfatal myocardial infarction [MI]), 455 deaths from cardiovascular disease, and 1,112 deaths from all causes. Men were classified as having: 1) no history of MI and diabetes, 2) late-onset diabetes (diagnosed at 60 years or undiagnosed diabetes [fasting blood glucose level >126.1 mg/dl]), 3) early-onset diabetes (diagnosed before age 60 years), or 4) prior MI. All men were followed up for all-cause mortality, cardiovascular disease morbidity, and the development of diabetes from the initial screening to June 2008. A Cox proportional hazards model to assess the age- and multivariate-adjusted hazard ratios was used.

Results:

Both early and late onset of diabetes were associated with a significantly increased risk of major CHD events and all-cause mortality compared with nondiabetic men who had no CHD, even after adjustment for conventional risk factors and novel risk markers (levels of C-reactive protein and von Willebrand factor and renal dysfunction). Only men with early-onset diabetes (associated with a duration of 16.7 years) showed risk similar to those with previous MI and no diabetes. The adjusted relative risks (95% confidence intervals) for major CHD events were 1.00 (reference), 1.54 (1.07-2.21), 2.39 (1.41-4.05), and 2.51 (1.88-3.36) for groups 1 through 4, respectively.

Conclusions:

The authors concluded that both early and late onset of diabetes are associated with increased risk of major CHD events and mortality, but only early onset of diabetes (associated with >10 years’ duration) appears to be a CHD equivalent.

Perspective:

The present analysis shows the importance of the timing of development of diabetes (linked to the duration of diabetes) on cardiovascular risk. Specifically, later onset of diabetes (those diagnosed at 60 years, associated with a mean diabetes duration of 4.9 years, and undiagnosed diabetes) had a CHD risk approximately half that in persons who developed diabetes before age 60 years, and had a mean duration of 16.7 years. These findings emphasize the critical importance of age at development of diabetes and of diabetes duration on cardiovascular risk, and the seriousness of the cardiovascular disease consequences of the emerging type 2 diabetes epidemic. Correctly identifying and treating individuals who are at highest risk of CHD will confer the most cost-effective public health strategy for primary prevention of CHD.

Clinical Topics: Prevention, Diet

Keywords: Myocardial Infarction, Blood Glucose, Diabetes Mellitus, Type 2, Cardiovascular Diseases, Coronary Disease, Risk Factors, Fasting


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