Effect of postprandial hyperglycaemia on blood viscosity in aged patients suffering from type 2 diabetes as compared with healthy volunteers.

Postprandial hyperglycaemia is an independent predictor of cardiovascular risk. Increased blood viscosity has been considered a major cardiovascular risk factor and may play a role in the vascular complications of diabetes. The present study aimed to verify whether blood viscosity is altered by the increased postprandial hyperglycaemia in aged type 2 diabetic patients. The whole blood viscosity, haematocrit, fibrinogen, glucose, insulin, total cholesterol, and triglyceride plasma levels, heart rate, and systolic and diastolic blood pressures were measured in 15 aged patients affected by type 2 diabetes and 15 healthy age-matched individuals before and 60 and 120 min after a test meal (670 kcal energy intake). In the basal condition, in both healthy control individuals and diabetic patients, the whole blood viscosity at higher shear rate (450/s) was significantly correlated in a negative way with the index of insulin resistance (P < 0.05), and in a positive way with the haematocrit value (P < 0.05) and the platelet count (P < 0.01). After the test meal, the whole blood viscosity significantly decreased (P < 0.01 or less) in aged healthy individuals, whereas it remained unchanged in type 2 diabetic patients. In conclusion, the negative action of postprandial hyperglycaemia in diabetes does not occur via a measurable increase of blood viscosity during that period. The decrease of blood viscosity observed during the postprandial period in normal individuals, however, points to the occurrence of alterations in the regulation of the haemorheological equilibrium in the postprandial period in aged type 2 diabetic patients.