Abnormalities of erythrocyte filtrability in diabetic microangiopathy.

In 30 ambulatory patients (14 men and 16 women), with diabetes mellitus (7 of type I and 23 of type II) of variable duration and with ages averaging 52.2 years, the degree of retinal microan giopathy was assessed along with the erythrocyte filtration rate (FR) and the percentage of glycosylated hemoglobin (HbA,). The FR was significantly (p < 0.001) lower among the diabetics (12.09 ± 2.71 JAI sec-I) than in the controls (15.80 ± 1.75). On the other hand, the level of HbA1 was significantly (p < 0.001) higher in the diabetics (12.26 ± 3.83) than in the control group (7.97 ± 1.47). The severity of the diabetic retinopathy was estimated as follows: degree Tin 10 patients, degree II in 10 patients al so, degree III in 4 patients and no abnormalities in 6 individuals. Among the patients the retinal lesions were significantly correlated (r = -0.46, p < 0.01) with the value of FR but were not affected by the level of HbA,. No significant correlation was detec ted between FR and HbA,. Our results suggest that, as a consequence of the metabolic abnormalities present in the diabe tics, the non-enzymatic glycosylation of hemoglobin A is increased. The rise of erythrocyte rigidity, while hampering blood-flow through already injured microvessels, could contribute to the development of retinal abnormalities irrespective of the HbA, le vel. Consequently, the abnormalities in the retinal microcirculation could, directly or indirectly, influence red cell filtrability, worsening the rheologic behaviour in the local microvessels.