Background: Elevated plasma fibrinogen levels which contribute to increases in whole blood viscosity and the augmented nonenzymatic glycosylation of hemoglobin underlying the reduced red blood cell deformability play important roles in the impaired blood fluid dynamics encountered in diabetes mellitus. The need for reliable monitoring and adequate determination of the physical parameters governing blood viscosity underlies the reason for studying the contributions of two risk factors in diabetes: plasma hyperfibrinogenaemia and red blood cell deformability.
Material/Methods: Using ESR spectroscopy, the viscosity of the solutions of fibrinogen and haemoglobin was determined based on the rotational mobility of two piperidine-1-oxyl spin labels: TEMPONE (4-oxo-2,2,6,6-tetramethylpiperidine-1-oxyl) and TEMPAMINE (4-amino-2,2,6,6-tetramethylpiperidine-1-oxyl).
Results: We demonstrated that: a/ certain physical parameters relevant to whole blood viscosity and fluid dynamics can be easily monitored in a routine laboratory practice with the use of ESR spectrometry; b/ various water-soluble piperidine-1-oxyl derivatives can serve this purpose; c/ the linear or quasi-linear relationships between the concentrations of either fibrinogen or haemoglobin and the relevant relative viscosity of the protein solution hold within relatively broad ranges of protein concentrations; d/ plasma viscosities correlated significantly with plasma fibrinogen levels but not with plasma albumin levels; e/ glycosylation of haemoglobin correlated very significantly with both the erythrocyte intracellular viscosity and the viscosity of haemoglobin solutions.
Conclusions: 1. Monitoring of plasma viscosity, intracellular red blood cell viscosity and the viscosities of haemoglobin solutions could be complementary determinations performed to evaluate the impaired blood fluid dynamics in diabetic state; 2. ESR spectroscopy appears to be a simple, reproducible and seful diagnostic tool for monitoring some properties of blood fluid dynamics.

Keywords: ESR spectroscopy, TEMPO derivatives, Diabetes Mellitus, Blood Viscosity, glycosylated haemoglobin, internal viscosity, erythrocyte deformability hyperfibrinogenaemia