Incident Silent Myocardial Infarction among People with Prediabetes—Results from Four Longitudinal Cohort Studies

Approximately 45% of first of myocardial infarctions (MI) are silent. People with diabetes are more likely to have MIs than those without diabetes. Little is known, however, about silent MIs (SMIs) among those with prediabetes. The prognosis of SMIs is similar to clinical MIs making timely detection imperative. We aimed to assess the association between prediabetes and incident SMI in four long duration cohort studies. We pooled data from the following studies: Cardiovascular Health, Atherosclerotic Risk in Communities, Health Aging and Body Composition, and Multi-Ethnic Study of Atherosclerosis (n=30,898). Population characteristics were: mean age 61.3 years, 45% male, 66.4% white, 40.0% had hypertension and 35.3% had hyperlipidemia. Diabetes status was based on fasting glucose (100-125mg/dL=prediabetes and >=126mg/dL=diabetes). Participants were also defined as having diabetes if they were taking medications for diabetes or reported a previous diagnosis. At baseline, 36% did not have diabetes, 50% had prediabetes and 14% had diabetes. Among participants with prediabetes, 3% experienced SMI over a mean follow-up of 9.6 years compared with 2% among those without diabetes. In Cox Proportional Hazards Models, we found an increased risk of incident SMI among those with prediabetes compared to those without diabetes (Hazard Ratio=1.25; 95% CI: 1.04-1.5, p=0.02), adjusting for age, sex, race, smoking status, hypertension, and high cholesterol. Significant baseline predictors of SMI in addition to having prediabetes included being male, older age, current smoking, and hypertension. People with prediabetes, comprising 50% of these cohort study populations, may be at increased risk for SMI, and could benefit from increased focus on prevention and treatment of cardiovascular risk factors.