Prevalence and clinical outcomes of undiagnosed diabetes mellitus and prediabetes among patients with high-risk non-ST-segment elevation acute coronary syndrome

Background We examined the prevalence of undiagnosed diabetes or prediabetes and associations with ischemic outcomes among non-ST-segment elevation acute coronary syndrome (ACS) patients. Methods We categorized 8795 EARLY ACS trial patients into one of the following groups: known diabetes (n = 2860 [32.5%]; reported on the case report form), undiagnosed diabetes (n = 1069 [12.2%]; no diabetes history and fasting glucose >= 126 mg/dL or hemoglobin A(1c) >= 6.5%), prediabetes (n = 947 [10.8%]; fasting glucose >= 110 to <126 mg/dL, or normal (n = 3919 [44.5%]). Adjusted associations of known diabetes, undiagnosed diabetes, and prediabetes (versus normal) with 30-day and 1-year outcomes were determined. Results Undiagnosed diabetes was associated with greater 30-day death or myocardial infarction (MI) (ORadj 1.28, 95% CI 1.05-1.57), driven primarily by greater 30-day mortality (ORadj 1.65, 95% CI 1.09-2.48). Known diabetic patients had 30-day death or MI outcomes similar to those of normal patients, but 30-day mortality was higher (ORadj 1.40, 95% CI 1.01-1.93). Prediabetic patients had 30-day death or MI outcomes similar to those of normal patients. One-year mortality was greater among known diabetic patients (HRadj 1.38, 95% CI 1.13-1.67) but not among those with undiagnosed diabetes or prediabetes. Conclusions Undiagnosed diabetes and prediabetes were common among high-risk non-ST-segment elevation ACS patients. Routine screening for undiagnosed diabetes may be useful since these patients seem to have worse short-term outcomes and deserve consideration of alternative management strategies.