In this large population-based study, the risk of cardiovascular and coronary mortality among older women with diabetes was similar to those with preexisting CVD. This increased mortality risk associated with diabetes was particularly apparent for longer duration of diabetes, and was independent of the presence of other cardiovascular risk factors.
Previous reviews of observational studies have summarized the cardiovascular risk associated with diabetes in comparison to those of adult with a history of CVD 
. However, most of the individual studies included in these meta-analyses have included middle-aged adults 
. The heterogeneity of the populations studied in meta-analyses is also an issue, as a recent report has established epidemiological differences in the cardiovascular risk among men and women with diabetes 
. For example, diabetes might confer a lower risk of coronary heart disease than previous myocardial infarction in middle-aged men 
, but a similar or higher risk in middle-aged women 
and only few data exist for older women 
. Therefore, our study provides important information to better assess the cardiovascular and coronary risk associated with diabetes in the population-based group of older women. In contrast to the limited power of traditional cardiovascular risk factors to predict CVD in older people 
, our results show that the presence of diabetes in older women - mean age of 75 years - was associated with total and cardiovascular mortality beyond demographics and other cardiovascular risk factors, and this association was as strong as the presence of pre-existing CVD.
In our study, the strong association of diabetes with total and cause-specific mortality might be explained by the long duration of exposure to diabetes. In middle-aged adults, the duration of diabetes plays a major role in the vascular risk 
. In an observational study including women with a long duration of diabetes, diabetes was associated with a greater risk of coronary mortality than a history of coronary heart disease 
. In older men, early-onset diabetes was associated with a higher risk of coronary heart disease than late onset diabetes 
. When stratifying our results between older women with a shorter duration of diabetes (late onset defined as duration of less than 10 years) and those with long-term diabetes, the latter seemed to be associated with a worse prognosis. In addition, the nearly 12-year mean follow-up period of our study implies an exposure to many years of diabetes in both groups. Thus, in older diabetic women the duration of diabetes appears to be a key risk factor and further studies should evaluate its importance for better tailoring preventive intervention.
Our study has several limitations. We were not able to use the complete follow-up period of the SOF cohort which started in 1986–1988, because information on history of CVD was only available at the third visit in 1991–1992. However, there was no evidence for a selective loss of follow-up for women with diabetes as compared to the rest of the study population between the first and the third visit. Moreover, because of the long remaining 12-year follow-up period of this analysis and the very large number of deaths, we believe that our estimates are reliable. We may have also underestimated the number of women with diabetes and those with known CVD, because information was obtained by self-report of physician diagnosis or use of anti-diabetic drugs for women with diabetes. Many women could have had a subclinical diabetes or CVD. However, these underestimations would have likely decreased associations with mortality, which we still found to be statistically significant. Because cholesterol measurements were available for 10% of the whole population, models including adjustment with LDL-cholesterol were less precise, although estimates remained significant. Residual confounding was possible due to unrecorded diabetes therapy, such as rosiglitazone, a diabetes medication first approved in 2000 and associated with an increased incidence of CHD among women with diabetes 
. However, over the bulk of follow-up time, this drug was not available. Baseline assessment of predictors was done in 1991–1992 and change in health behavior across recent decades might have influenced our results. However, diabetes has been shown to be associated with the same risk of cardiovascular mortality independently of the time-period 
. Causes of deaths were based upon death certificates, but causes of death were confirmed by hospital discharge summaries and were adjudicated. These data have also a number of strengths: the large population of older women, the long follow-up period with a minimal loss to follow-up, and the very high number of events.