The study evaluated more than 8,000 participants from the Framingham Heart Study original and offspring cohorts. Participants were divided into two groups: those who attended clinic examinations between 1950 and 1966 and those who were examined between 1977 and 1995. Scientists compared the CVD incidence rates of those with and without diabetes between the earlier and later time periods.

Diabetes is becoming more common in the U.S. due to many factors, including an increase in obesity and in the number of older adults. Diabetes will therefore be an increasingly important cause of cardiovascular disease in the U.S.

Between the earlier and later periods, the rate of cardiovascular events among diabetic patients fell from 286.4 to 146.9 per 10,000 person-years, a reduction of nearly 50%, lead author Dr. Caroline S. Fox, from the National Institutes of Health in Bethesda, Maryland, and colleagues note.

In patients without diabetes, the rate of events decreased from 84.6 to 54.3 per 10,000 person-years during the study period, a reduction of 35.4%.

Despite the encouraging trend seen for diabetics, their twofold increased risk of cardiovascular events, compared with non-diabetic subjects, still held steady.

The researchers conclude that "both aggressive treatment of conventional cardiovascular disease risk factors and further research on diabetes-specific factors contributing to cardiovascular disease risk are needed to further reduce the high absolute risk of cardiovascular disease still experienced by persons with diabetes."