Daily low-dose aspirin and incident type 2 diabetes in community-dwelling healthy older adults: a post-hoc analysis of efficacy and safety in the ASPREE randomised placebo-controlled trial.

backgroundInflammation has been implicated in the pathogenesis of diabetes. This study investigated the randomised treatment effect of low-dose aspirin on incident type 2 diabetes and fasting plasma glucose (FPG) concentrations among older adults.

methodsASPREE was a double-blind, placebo-controlled trial of daily oral low-dose aspirin. The study population included community-dwelling individuals aged 70 years or older (≥65 years for US minority ethnic groups) in the USA and Australia who were free of cardiovascular disease, independence-limiting physical disability, or dementia. For the post-hoc analysis, we excluded participants with diabetes at baseline or with incomplete or missing incident diabetes data during follow-up. Participants were randomly assigned 1:1 to oral 100 mg daily enteric-coated aspirin or placebo. Incident diabetes was defined as self-reported diabetes, commencement of glucose-lowering medication, or a FPG concentration of 7·0 mmol/L or more assessed at annual follow-up visits among participants with no diabetes at baseline. We used Cox proportional hazards models and mixed-model repeated measures to assess the effect of aspirin on incident diabetes and FPG concentrations in the intention-to-treat population. We assessed major bleeding in participants who had taken at least one dose of study medication.

findingsBetween March 10, 2010, and Dec 24, 2014, a total of 16 209 participants were included (8086 [49·9%] randomly assigned to aspirin and 8123 [50·1%] randomly assigned to placebo). During a median follow-up of 4·7 years (IQR 3·6-5·7), 995 (in 6·1% individuals) incident cases of type 2 diabetes were recorded (459 in the aspirin group and 536 in the placebo group). Compared with placebo, the aspirin group had a 15% reduction in risk of incident diabetes (hazard ratio 0·85 [95% CI 0·75 to 0·97]; p=0·013) and a slower rate of increase in FPG concentration at year 5 (between-group difference estimate -0·048 mmol/L [95% CI -0·079 to -0·018]; p=0·0017). Major bleeding (major gastrointestinal bleeding, intracranial bleeding, and clinically significant bleeding at other sites) occurred in 510 (3·2%) of 16 104 participants (300 [3·7%] in the aspirin group and 210 [2·6%] in the placebo group). Compared with placebo, the aspirin group had a 44% increase in risk of major bleeding (hazard ratio 1·44 [95% CI 1·21 to 1·72]; p<0·0001).

interpretationAspirin treatment reduced the incidence of type 2 diabetes and slowed the increase in FPG concentration but increased major bleeding among community-dwelling older adults. Given the increasing prevalence of type 2 diabetes among older adults, the potential for anti-inflammatory agents such as aspirin to prevent type 2 diabetes or improve glucose levels warrants further study with a comprehensive assessment of all potential safety events of interest.

fundingUS National Institute on Aging, US National Cancer Institute, National Health and Medical Research Council of Australia, Monash University, and the Victorian Cancer Agency.