Two-hour post-load plasma glucose levels are associated with carotid intima-media thickness in subjects with normal glucose tolerance

AimsElevated post-load plasma glucose levels may increase the risk of cardiovascular disease, even when they are within the normoglycaemic range. We examined the association of carotid artery intima-media thickness, a marker of early atherosclerosis, with glycaemic variables, including post-load plasma glucose levels, in Japanese subjects with normal glucose tolerance. MethodsThe study participants were 663 Japanese subjects with normal glucose tolerance (565 men, mean age 479years) who underwent both a 75-g oral glucose tolerance test and carotid artery intima-media thickness measurement by B-mode ultrasonography during a health examination. Associations between maximal common carotid artery intima-media thickness and fasting plasma glucose, 1-h and 2-h plasma glucose during an oral glucose tolerance test, and HbA(1c) were examined. ResultsThe carotid artery intima-media thickness gradually increased across the tertiles of 1-h plasma glucose, 2-h plasma glucose and HbA(1c). In multiple linear regression analysis, 2-h plasma glucose (=0.09, P=0.012), as well as age, male gender, hypertension, dyslipidaemia, and current smoking were independent determinants of carotid artery intima-media thickness. In contrast, other glycaemic variables were not independent determinants of carotid artery intima-media thickness. The carotid artery intima-media thickness in hypertensive subjects with the highest tertile of 2-h plasma glucose [0.70 (95%CI 0.64-0.76) mm] was significantly greater than in normotensive subjects, with the lowest tertile of 2-h plasma glucose [0.60 (95%CI 0.58-0.63) mm, P=0.037], even after adjusting for the multiple potential confounders. ConclusionsThe 2-h plasma glucose during an oral glucose tolerance test was positively and independently associated with carotid artery intima-media thickness in Japanese subjects with normal glucose tolerance. In particular, the combination of elevated 2-h plasma glucose and hypertension may contribute to an increased carotid artery intima-media thickness.