Dysglycaemia and the risk of acute myocardial infarction in multiple ethnic groups: an analysis of 15,780 patients from the INTERHEART study

Aims/hypothesisAlthough diabetes is an established risk factor for myocardial infarction (MI), disease control may vary. HbA1c is a reliable index of ambient glucose levels and may provide more information on MI risk than diabetes status.MethodsThe relationship between HbA1c levels in MI patients and controls who participated in the 52 country INTERHEART study was analysed.ResultsIn 15,780 participants with a HbA1c value (1,993 of whom had diabetes), the mean (SD) levels for HbA1c were 6.15% (1.10) in the 6,761 MI patients and 5.85% (0.80) in the control participants. After adjustment for age, sex and nine major MI risk factors (including diabetes), higher HbA1c fifths above the lowest fifth (HbA1c <5.4%) were associated with progressively higher OR of MI, with OR for the highest HbA1c fifth (≥6.12%) being 1.55 (95% CI 1.37–1.75). When analysed as a continuous variable after adjustment for the same factors, every 1% higher HbA1c value was associated with 19% (95% CI 14–23) higher odds of MI, while every 0.5% higher HbA1c was associated with 9% higher odds of MI (95% CI 7–11). Concordant relationships were noted across subgroups, with a higher OR noted in younger people, patients without diabetes or hypertension, and those from some regions and ethnicities.Conclusions/interpretationThe HbA1c value provides more information on MI odds than self-reported diabetes status or many other established risk factors. Every 1% increment independently predicts a 19% higher odds of MI after accounting for other MI risk factors including diabetes.