Objective: Carotid intima-media thickness (IMT) has proved to be an independent marker of preclinical atherosclerosis. The aim of this study was to determine whether carotid IMT is associated with the plasma glucose concentration in the fasting state, after loading with oral glucose, or with the insulin sensitivity index (ISI) in nondiabetic subjects with different levels of glucose intolerance and insulin resistance.
Design: Cross-sectional study.
Patients: A total of 160 nondiabetic subjects (147 from our obesity-overweight clinic and 13 healthy normal subjects) were included in the present study, among them 33 had normal glucose tolerance (NGT), 13 had impaired fasting glucose (IFG), 80 had impaired glucose tolerance (IGT) and 34 had both IFG and IGT.
Measurements: Carotid IMT was assessed in the common carotid artery by a high-resolution B-mode ultrasound system. Plasma glucose was measured after fasting and at 30 min, 1, 2 and 3 h after a standard 75-g load of glucose. The ISI was calculated from the frequent sampling intravenous glucose tolerance test (FSIGT). Results The IMT values in the NGT group were lower than those in the IFG, IGT and IFG + IGT groups (P < 0.03). No statistical difference in IMT values was found among the latter three groups. Univariate correlation analyses showed that the IMT was positively associated with age, plasma glucose concentrations 1 and 2 h after glucose loading, and serum concentration of low density lipoprotein (LDL) cholesterol (r=0.39, 0.22, 0.25 and 0.18, respectively, P<0.05). Multiple regression analysis showed that only age, plasma glucose concentration 2 h after glucose loading, and LDL cholesterol appeared to be significant correlates of the IMT (P<0.0001), whereas the ISI was not.
Conclusions: In nondiabetic subjects with various degrees of glucose intolerance, there was a significant increase in IMT in those with IFG and IGT. Significant determinants of IMT, an indicator of preclinical atherosclerosis, include hyperglycaemia 2 h after a glucose load, age and LDL cholesterol, whereas fasting glucose concentration and the ISI were not significantly associated with IMT.