Diabetic rats develop vascular remodeling over time. Wall thickness (a), lumen diameter (b), W:L ratio (c) and CSA (d) were measured in MCAs under passive conditions in the fully dilated state. While there was no difference in these structural indices between control and diabetic rats at 10 weeks, by 18 weeks all indices were increased in diabetes. Metformin treatment starting at the onset of diabetes prevented vascular remodeling. Mean ± SEM, n=7–14, *p<0.05 vs 10-week control, **p<0.05 vs 18-week diabetes, *** p<0.05 vs 18-week control,