Six studies (7,907 participants reported in tables, 7,374 in abstract) were included. Three were RCTs (4,846 participants), and three (3,061 participants) were subgroup analyses of people with diabetes from larger trials. Five were placebo controlled, and one was open label (no comparative treatment).
Compared to controls there was no statistically significant effect of aspirin on cardiovascular events (five studies), myocardial infarction (six studies), ischaemic stroke (three studies) or all-cause mortality (three studies). Three studies reported on bleeding with a total of 50 events in the aspirin groups and 36 in the control groups, there was no statistically significant difference in risk of bleeding between groups.