RHEOLOGICAL AND MICROVASCULAR PARAMETERS IN DIABETIC PERIPHERAL NEUROPATHY

1. In order to determine whether rheological changes occur in neuropat hic diabetic patients in the absence of smoking, proteinuria, retinopa thy or other factors thought to influence haemorheology, three groups of subjects were studied; 24 non-diabetic control subjects (C), 24 non -neuropathic (D) and 24 neuropathic (N) diabetic patients, The groups were matched for age, sex, type and duration of diabetes, No patient o r control was a current smoker, No patient had clinically detectable r etinopathy or microalbuminuria, Neuropathy was defined as a peroneal c onduction velocity < 40 ms(-1). All subjects were tested resting semi- recumbent after a light breakfast. 2. There were no significant differ ences in rheological or microvascular parameters between uncomplicated diabetic patients and non-diabetic control subjects, although peronea l nerve motor conduction velocity was significantly reduced in otherwi se uncomplicated diabetic patients [C 51.7 +/- 6.0 ms(-1) (mean +/- SD ) versus D 45.1 +/- 5.2 ms(-1) (P < 0.05 C versus D)]. 3. Transcutaneo us oxygen and laser Doppler flux measured at 44 degrees C were higher in control subjects than in neuropathic diabetic patients [C 76 +/- 16 mmHg versus D 71 +/- 10 mmHg versus N 63 +/- 9 mmHg, and C 72 +/- 40 flow units versus D 64 +/- 41 flow units versus N 50 +/- 26 flow units respectively (both P not significant C versus D, P < 0.05 N versus C) . 4. Erythrocyte aggregation, plasma viscosity and plasma fibrinogen w ere all significantly higher in the neuropathic diabetic patients comp ared with nondiabetic control subjects (all P < 0.05 N versus C), Eryt hrocyte filtration was not significantly different between groups but was lower in diabetic patients, Whole-blood viscosity (corrected to 45 % haematocrit) was significantly higher at both high (100 s(-1)) and l ow (1 s(-1)) shear rates in neuropathic diabetic patients than in non- diabetic control subjects (both P not significant C versus D, P < 0.05 N versus C). There were no significant differences in whole-blood vis cosity at a shear rate of 0.01 s(-1). 5. In summary, there were no sig nificant differences in rheological or microvascular parameters betwee n matched groups of uncomplicated diabetic patients and control subjec ts, but erythrocyte aggregation, fibrinogen and plasma and corrected w hole-blood viscosity were all significantly different in neuropathic d iabetic patients compared with control subjects, as were assessments o f microvascular flow, These results suggest that haemorheological chan ges are associated with disturbances of microvascular flow and diabeti c peripheral neuropathy in the absence of other diabetic complications .