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

Although diabetes is an established risk factor for myocardial infarction (MI), disease control may vary. HbA_1c is a reliable index of ambient glucose levels and may provide more information on MI risk than diabetes status.

The relationship between HbA_1c levels in MI patients and controls who participated in the 52 country INTERHEART study was analysed.

In 15,780 participants with a HbA_1c value (1,993 of whom had diabetes), the mean (SD) levels for HbA_1c 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 HbA_1c fifths above the lowest fifth (HbA_1c <5.4%) were associated with progressively higher OR of MI, with OR for the highest HbA_1c 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 HbA_1c value was associated with 19% (95% CI 14–23) higher odds of MI, while every 0.5% higher HbA_1c 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.

The HbA_1c 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.