Haemoglobin A1c is associated with carotid intima-media thickness in a Chinese population

The association between haemoglobin A1c (HbA1c) levels and subclinical atherosclerosis in carotid arteries in Chinese populations is unknown. AIM, DESIGN AND METHODS: The objective of this study was to investigate this relationship and evaluate the ability of HbA1c levels to predict carotid atherosclerosis in a Chinese population. This was a cross-sectional study, which included 541 subjects without known diabetes (Taiwan Lifestyle Study). About 67 (9·2%) subjects were newly diagnosed with diabetes during the study. Carotid intima-media thickness (IMT) and the presence of carotid plaques were determined using ultrasonography.

The HbA1c level in all subjects was positively correlated with carotid IMT (β = 0·018, P = 0·03) after being adjusted for age, gender, smoking, low-density lipoprotein cholesterol level, hypertension and body mass index. HbA1c level was higher in subjects with plaques in carotid arteries (P = 0·01). There was a positive and linear relationship between HbA1c levels and the probability of having plaques, thickened carotid IMT or both (P for all comparisons, <0·05). The ability of HbA1c levels to predict thickened carotid IMT or the presence of plaques was only modest {the optimal cutoff of HbA1c level [5·7%] was determined from the receiver operating characteristic (ROC) curve (sensitivity = 67%, specificity = 61%) and the area under the ROC curve [0·666]}.

Thus, HbA1c level is associated with subclinical atherosclerosis in carotid arteries in a Chinese population. The relationship is linear without an inflection point. However, HbA1c criterion is not a useful marker for the identification of subclinical atherosclerosis.