Elevated one-hour post-load plasma glucose levels identifies subjects with normal glucose tolerance but early carotid atherosclerosis

Objective: To examine whether individuals with normal glucose tolerance (NGT), whose 1-h post-load plasma glucose is >= 155 mg/dl, or with impaired glucose tolerance (IGT) have an increased carotid intima-media thickness (IMT), as compared with NGT individuals with 1-h post-load plasma <155 mg/dl. Methods: Atherosclerosis risk factors, oral glucose tolerance test (OGTT), and ultrasound manual measurement of IMT were analyzed in 400 non-diabetic Caucasians. Results: As compared with individuals with a 1-h post-load plasma glucose <155 mg/dl, NGT individuals with a 1-h post-load plasma glucose >= 155 mg/dl exhibited higher hsCRP (2.0 +/- 1.5 vs. 1.5 +/- 1.0, P = 0.008), and IMT (0.82 +/- 0.20 vs. 0.71 +/- 0.16; P=0.006), and lower insulin sensitivity (71 +/- 39 vs. 105 +/- 57; P < 0.0001), and IGF-1 levels (214 +/- 88 vs. 176 +/- 49; P < 0.03). No significant differences were observed in metabolic and cardiovascular risk factors between IGT and NGT subjects with a 1-h post-load glucose >= 155 mg/dl. Of the three glycemic parameters, 1-h and 2-h post-load glucose, but not fasting glucose, were significantly correlated with IMT. In a stepwise multivariate regression analysis in a model including age, gender, and a variety of atherosclerosis risk factors, the three variables that remained significantly associated with IMT were age (P < 0.0001), BMI (P < 0.0001), and 1-h post-load glucose (P = 0.02) accounting for 20.2% of its variation. Conclusions: NGT subjects with a 1-h post-load glucose >= 155 mg/dl have an atherogenic profile similar to IGT individuals. These data suggest that a cutoff point of 155 mg/dl for the 1-h post-load glucose during OGTT may be helpful in the identification of NGT subjects at increased risk for cardiovascular disease. (C) 2009 Elsevier Ireland Ltd. All rights reserved.