The leading cause of mortality in people with diabetes is cardiovascular disease (CVD), which is estimated to lead to more than 70% of deaths in this population. Aspirin offers promise for the primary prevention of CVD in people with diabetes, but controversy regarding the risks and benefits of such treatment has led to inconsistent recommendations. To determine the efficacy of aspirin in the primary prevention of CVD in people with diabetes, researchers conducted an updated meta-analysis of the literature as well as a meta-analysis of individual patient data from three trials.

The meta-analysis of the literature included 12 randomized controlled trials with 34,227 participants that compared aspirin with placebo or no treatment in adults with diabetes with no history or clinical evidence of CVD. The median duration of follow-up was five years. Compared with placebo or no treatment, aspirin significantly reduced the risk of major adverse cardiovascular events (a composite of nonfatal myocardial infarction, nonfatal stroke, and cardiovascular death). Aspirin use, however, was not associated with a significant decrease in the risk of all-cause mortality.

Subgroup analyses suggested possible differences in the effects of aspirin in people with diabetes, depending on treatment duration, dosage, and smoking status. Aspirin use for five years or less, but not for more than five years, was associated with a lower risk of myocardial infarction. Aspirin dosage of 100 mg/day or less and treatment for five years or more were associated with a lower risk of stroke. Pooled analysis of individual data from the three trials showed that aspirin reduced the risk of major adverse cardiovascular events in nonsmokers compared with smokers.

The authors conclude that the use of low-dose aspirin may need to be individualized and based on each person's baseline CVD and bleeding risk. Limitations of this study include varying definitions of clinical outcomes and selective reporting in some studies. The researchers also note that they were unable to perform detailed subgroup analyses owing to limited data and an inconsistent manner of reporting across the studies.

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