Association Between Hemoglobin A1c and Development of Cardiovascular Disease in Canadian Men and Women Without Diabetes at Baseline: A Population‐Based Study of 608 474 Adults

Abstract

Background We examined the association between hemoglobin A1c (HbA1c) and the development of cardiovascular disease (CVD) in men and women, without diabetes or CVD at baseline. Methods and Results This retrospective cohort study included adults aged 40 to <80 years in Alberta, Canada. Men and women were divided into categories based on a random HbA1c during a 3‐year enrollment period. The primary outcome of CVD hospitalization and secondary outcome of combined CVD hospitalization/mortality were examined during a 5‐year follow‐up period until March 31, 2021. A total of 608 474 individuals (55.2% women) were included. Compared with HbA1c 5.0% to 5.4%, men with HbA1c of 5.5% to 5.9% had an increased risk of CVD hospitalization (adjusted hazard ratio [aHR], 1.12 [95% CI, 1.07–1.19]) whereas women did not (aHR, 1.01 [95% CI, 0.95–1.08]). Men and women with HbA1c of 6.0% to 6.4% had a 38% and 17% higher risk and men and women with HbA1c ≥6.5% had a 79% and 51% higher risk of CVD hospitalization, respectively. In addition, HbA1c of 6.0% to 6.4% and HbA1c ≥6.5% were associated with a higher risk (14% and 41%, respectively) of CVD hospitalization/death in men, but HbA1c ≥6.5% was associated with a 24% higher risk only among women. Conclusions In both men and women, HbA1c ≥6.0% was associated with an increased risk of CVD and mortality outcomes. The association between CVD and HbA1c levels of 5.5% to 5.9%, considered to be in the “normal” range, highlights the importance of optimizing cardiovascular risk profiles at all levels of glycemia, especially in men.