Newly diagnosed diabetes at acute myocardial infarction presentation: higher glycemic burden, more multivessel-disease but similar clinical severity to non-diabetics

Introduction Diabetes mellitus (DM) affects around 10–15% of the general population and up to 30% of patients with acute myocardial infarction (AMI). Established DM is linked to extensive coronary atherosclerosis and poorer outcomes, yet the condition often remains undiagnosed at AMI presentation. Up to 15% of AMI patients are found to have previously unrecognised diabetes (HbA1c ≥6.5%) during admission, representing a subgroup without prior risk modification but with likely prolonged hyperglycemia. Whether newly diagnosed DM at AMI presentation is associated with similar severity to established DM remains unclear. Objectives This study aimed to compare clinical characteristics, extent of coronary artery disease, and acute hemodynamic severity among patients admitted with AMI stratified by diabetic status: Established diabetes mellitus (DM known), newly diagnosed diabetes mellitus (HbA1c ≥6.5% at admission, previously undiagnosed) and non-diabetic patients). Methods A retrospective analysis was conducted including 4,274 patients admitted with AMI to the Cardiac Intensive Care Unit of our institution, a tertiary hospital, between 2012 and 2024. Patients were stratified into three groups: those with previously known DM (n = 1,540), newly diagnosed DM (n = 184), and non-diabetic patients (n = 2,550). Results Mean age at admission was 69.8 ± 11.41 years for known diabetics, 65.9 ± 12.41 years for newly diagnosed diabetics, and 64.1 ± 13.37 years for non-diabetics. Among known diabetics, 82.7% had hypertension and 68.8% had dyslipidemia, with a mean HbA1c of 7.7 ± 3.1%. In the newly diagnosed group, 60.9% were hypertensive and 42.8% dyslipidemic, with a markedly elevated HbA1c of 10 ± 2.8%. Among non-diabetics, 55.8% had hypertension and 44% dyslipidemia. Regarding the burden of atherosclerotic disease, 28.7% of known diabetics had a prior history of coronary artery disease and 15.9% had cerebrovascular disease or peripheral arterial disease (PAD). Among newly diagnosed diabetics, the prevalence was 20.7% and 6%, respectively. In non-diabetics, these figures were 12.4% and 6.4%. In terms of coronary anatomy, triple-vessel disease was identified in 24.2% of known diabetics, compared to 18.8% in newly diagnosed diabetics and 11.4% in non-diabetics. Vasoactive support with dobutamine was required in 15.9%, 10.9%, and 11.4% of patients, respectively, while norepinephrine was used in 15.6%, 9.8%, and 14.6%. Conclusions Newly diagnosed diabetes was found in 4.3% of AMI patients, showing marked glycemic dysregulation suggestive of long-standing undetected disease. They displayed intermediate coronary complexity between established diabetics and non-diabetics. Routine HbA1c screening in acute coronary syndromes is crucial for early identification and targeted secondary prevention.