One-hour post-load hyperglycemia by 75g oral glucose tolerance test as a novel risk factor of atherosclerosis

Postprandial hyperglycemia is considered as a risk factor of cardiovascular disease. We hypothesized that early post-load hyperglycemia might be more useful surrogate marker to assess atherosclerosis than plasma glucose (PG) level at 120 minutes because the peak of post-load glucose by 75gOGTT is usually shown at 60 minutes. 75gOGTT and carotid echography were investigated in 108 subjects who visited our hospital to examine impaired glucose tolerance. The association of post-load plasma glucose and insulin levels with intima-media thickness (IMT) was examined. Simple correlation analyses showed that fasting PG (FPG) (r=0.26, p=0.013), PG60 (r=0.40, p<0.001), PG90 (r=0.29, p=0.008), area under curve for PG (AUC-PG) (r=0.33, p=0.003), HbA1c (r=0.30, p=0.005), amount of PG increase at 60 minutes (PGΔ60) (r=0.39, p=0.002), and PGΔ90 (r=0.27, p=0.016), were significantly correlated with IMT. Multiple regression analysis using IMT as a dependent variable and PG60, FPG, HbA1c, and AUC-PG as independent variables showed that PG60 was only significantly and positively correlated with IMT (β=0.59, p=0.042). Moreover, PG60 and PGΔ60 were significantly and positively associated with IMT even after additional adjustment for classical atherosclerosis risk factors (β=0.30, p=0.005 and β=0.50, p=0.037, respectively). The cut-off values of PG60 and PGΔ60 to detect atherosclerosis (IMT > 1.1mm) were 188 and 101 mg/dL, respectively (p<0.01). These findings show that early post-load hyperglycemia, particularly PG60 is a novel risk factor of atherosclerosis and useful to assess it.