Elevated 1-h post-challenge plasma glucose levels in subjects with normal glucose tolerance or impaired glucose tolerance are associated with whole blood viscosity.

Abstract

It has been suggested that glucose levels ≥155mg/dl at 1-h during an oral glucose tolerance test (OGTT) may predict development of type 2 diabetes and cardiovascular events among adults with normal glucose tolerance (NGT 1h-high). Studies showed a link between increased blood viscosity and type 2 diabetes. However, whether blood viscosity is associated with dysglycemic conditions such as NGT 1h-high, impaired glucose tolerance (IGT) or impaired fasting glucose (IFG) is unsettled. 1723 non-diabetic adults underwent biochemical evaluation and OGTT. A validated formula based on hematocrit and total plasma proteins was employed to estimate whole blood viscosity. Subjects were categorized into NGT with 1h glucose <155mg/dL (NGT-1h-low), NGT-1h-high, IFG and/or IGT. Hematocrit and blood viscosity values appeared significantly higher in individuals with NGT 1h-high, IFG and/or IGT as compared to NGT 1h-low subjects. Blood viscosity was significantly correlated with age, waist circumference, blood pressure, HbA1c, fasting, 1- and 2-h post-challenge insulin levels, total cholesterol and low-density lipoprotein, triglycerides, fibrinogen, white blood cell, and inversely correlated with high-density lipoprotein and insulin sensitivity. Of the four glycemic parameters, 1-h post-challenge glucose showed the strongest correlation with blood viscosity (β=0.158, P<0.0001) in a multivariate regression analysis model including several atherosclerosis risk factors. Our results demonstrate a positive relationship between blood viscosity and 1-h post-challenge plasma glucose. They also suggest that a subgroup of NGT individuals with 1-h post-challenge plasma >155mg/dl have increased blood viscosity comparable to that observed in subjects with IFG and/or IGT.