The effect of diabetes on the red blood cell (RBC) deformability and its
association with histological vascular changes was investigated in 35
streptozotocin-induced diabetic Wistar rats in a 30-day experiment and
compared to 10 controls. RBC deformability was significantly impaired in
the diabetic rats on day 5 (p<0.001) and continued to deteriorate until
day 20. On the 20(th) day, the diabetic rats were randomly divided into
two groups (group A: insulin-treated; group B: non-insulin-treated). A
slight, non-significant (p=0.20) improvement in RBC deformability was
noticed in the insulin-treated group. In vitro incubation of RBCs with
insulin did not improve the acquired RBC rigidity in either diabetic
group. In contrast, it caused a significant reduction in
RBC-deformability in the controls. On day 30, histological examination
of arterial specimens from various sites revealed moderate to
significant thickening in medium- and small-size artery and arteriole
walls in both diabetic groups, with no evidence of diabetes-related
changes in large, elastic-type arteries. No vascular changes were
noticed in nine diabetic rats that succumbed between days 10 and 15. The
results of this study indicate that reduced RBC deformability is an
early manifestation of abnormal blood rheology in experimental diabetes,
and precedes the evolution of vascular changes