Blood Viscosity, Hematocrit Linked to Diabetes Risk

Elevated blood viscosity and hematocrit are associated with an increased risk of insulin resistance and type 2 diabetes, according to a new report

Blood viscosity is inversely related to flow, the authors explain, and might thereby contribute to flow-related insulin resistance.

Dr. Leonardo J. Tamariz from the University of Miami School of Medicine, Florida and colleagues analyzed data from the Atherosclerosis Risk in Communities (ARIC) Study.

Elevated whole blood viscosity, they found, was associated with higher body mass index, waist circumference, waist/hip ratio, systolic blood pressure, fasting glucose, insulin, fibrinogen, white blood cells, and triglyceride levels and with lower high density lipoprotein cholesterol levels.

Whole blood viscosity correlated strongly with hematocrit but only weakly with plasma proteins.

During 9 years of follow-up, whole blood viscosity was positively associated with diabetes, with a nearly 2-fold gradient in diabetes risk between the lowest and highest quartile of estimated whole blood viscosity.

In multivariate analyses, the highest quartile of whole blood viscosity was associated with a 68% increased incidence of type 2 diabetes. Similar risk gradients were shown for hematocrit and plasma protein, the researchers note.

Blood viscosity predicted the development of diabetes in both men and women, in whites and African Americans, and in smokers and nonsmokers, the investigators say.

“The main implication of our study is that elevated blood viscosity might be an independent risk factor for type 2 diabetes,” the authors conclude. “This work supports the hypothesis that decreased delivery of substrate leads to the development of insulin resistance and type 2 diabetes.”

“Whether modification of blood viscosity might influence diabetes risk awaits further study,” they add.

Am J Epidemiol  Nov. 24, 2008;168:1153-1160.