To assess the effects of high blood glucose concentration on glomerular changes after the acute mesangial cell injury in the rat, the monoclonal anti-Thy1.1 antibody OX-7 was injected into streptozoticin-induced diabetic rats or normal rats. The increase in proliferating cell nuclear antigen-positive cells in glomeruli at day 4 and glomerular hypercellularity at day 18 was less prominent in diabetic rats than in normal rats. The expansion of mesangial matrix area assessed by fibronectin immunostaining was more prominent, and segmental glomerulosclerosis was observed at day 60 in the diabetic rats. These data suggest that the insulin-deficient group may reflect impaired "wound-healing," leading to the prolonged ECM accumulation under the hyperglycemic condition in vivo.