Abstract P434: The Relationship Between Level of Glycemic Control and First Manifestation of Coronary Artery Disease (CAD) Differs by Sex in Type 1 Diabetes (T1D)
The nature of the association between glycemic control and CAD in T1D is unclear. The Pittsburgh Epidemiology of Diabetes Complications (EDC) study of childhood-onset T1D has not demonstrated a consistent relationship between glycemic control and incidence of CAD, with neither baseline HbA1c nor average HbA1c over follow-up reliably predicting CAD. However, it is possible that glycemic control may influence the type of first CAD event observed. As CAD often manifests differently in men and women, our objective was to examine whether the manifestation of CAD differs by glycemic control up to the time of the CAD event separately by sex.
Data are from 604 (304 men, 300 women) participants in the Pittsburgh EDC Study of childhood-onset (<17 years old) type 1 diabetes without prevalent CAD at baseline and represent 20 years of follow-up for CAD incidence ascertainment. Participants were first assessed 1986-1989 (mean age, 28 and duration, 19 years), with 8 subsequent exams occurring approximately every 2 years thereafter. First CAD event was divided into 5 categories: fatal event/CAD death, nonfatal myocardial infarction (MI), revascularization/stenosis >=50%, ischemia (Minnesota codes 1.3, 4.1, 4.3, 5.1, 5.3, 7.1), or angina. The average HbA1c from baseline until CAD event or last follow-up for noncases was calculated (median # HbA1c measures=4); the median average HbA1c was 8.7%. This value was used as a cut point to divide the cohort into 2 groups: persons with HbA1c≥8.7% at all study visits prior to CAD incidence (80 men, 60 women) versus all others (224 men, 240 women).
In women, the 20-year incidence of CAD was 40% (n=24) and 24.6% (n=59) in the consistently high HbA1c group and all others, respectively (p=0.02). In men, CAD incidence was 38.8% (n=31) and 28.6% (n=64) in the high HbA1c group and all others, respectively (p=0.09). Of the CAD cases, nonfatal MI was a significantly more frequent first event in the consistently high HbA1c group compared to all others in both men (48.4% v 21.9%, p=0.009) and women (37.5% v 15.3%, p=0.04). Angina was a significantly less frequent first event in the consistently high HbA1c group in women (25% v 52.5% in all others, p=0.02), but no significant difference in angina incidence by HbA1c group was observed in men. Fatal CAD was a marginally more frequent first event in the high HbA1c group in women (16.7% v 3.4%, p=0.06), but did not differ by HbA1c in men. No differences for revascularization or ischemia as first events were seen by HbA1c group in either sex.
These results suggest that, in T1D, glycemic control may influence the manner of CAD manifestation, in particular nonfatal MI and angina, and that this effect may differ by sex. Particularly, there may be a need for more aggressive monitoring and treatment of CAD risk factors in women with high HbA1c, as they may be at higher risk of fatal events.
- © 2013 by American Heart Association, Inc.