Objective: To test the hypothesis that A1C is associated with subclinical cardiovascular disease (CVD) in a population without evident diabetes, after adjusting for traditional CVD risk factors and BMI.
Research design and methods: This was a cross-sectional study of 5,121 participants without clinically evident CVD or diabetes (fasting glucose > or =7.0 mmol/l or use of diabetes medication), aged 47-86 years, enrolled in the Multi-Ethnic Study of Atherosclerosis (MESA). Measurements included carotid intimal-medial wall thickness (CIMT) and coronary artery calcification (CAC). Results were adjusted for age, sex, ethnicity, smoking, systolic blood pressure, LDL cholesterol, HDL cholesterol, antihypertensive medication use, lipid-lowering medication use, and BMI.
Results: Compared with those in the lowest quartile for A1C ([mean +/- SD] 5.0 +/- 0.2%), participants in the highest quartile (6.0 +/- 0.3%) had higher adjusted mean values for common CIMT (0.85 vs. 0.87 mm, P = 0.003) and internal CIMT (1.01 vs. 1.08 mm, P = 0.003). A1C quartile was not associated with prevalence of CAC in the entire cohort (P = 0.27); however, the association was statistically significant in women (adjusted prevalence of CAC in lowest and highest A1C quartiles 37.5 vs. 43.0%, P = 0.01). Among those with some CAC, higher A1C quartile tended to be associated with higher CAC score, but the results were not statistically significant (adjusted P = 0.11).
Conclusions: In this multiethnic cohort, there were small, positive associations between A1C, common CIMT, and internal CIMT in the absence of clinically evident diabetes. An association between higher A1C and CAC prevalence was evident only in women.