The effect of diabetes mellitus on remodeling of the injured rat carotid artery

Restenosis after angioplasty is more prevalent among patients with diabetes mellitus (DM) than in nondiabetics (ND). To determine if reendothelialization is slowed or intimal thickening is enhanced by diabetes, we performed carotid balloon denudation with a 2F Fogarty catheter on an inbred strain of diabetic BB rats (<60 days from onset of insulin requirement) and on nondiabetic littermates as controls. All diabetic rats received insulin while controls did not and the latter group remained non-glycosuric during the study. Evans blue staining and perfusion fixation were performed in groups of rats 2, 3, 4 and 12 weeks to evaluate endthelial growth. Intimal thickening was evaluated by light microscopy and planimetry of arterial histologic sections and showed no significant differences between the two groups. At 4 weeks intimal area was 0.17+/-0.01 (n=13) in DM rats and 0.18+/-0.02 (n=7) in ND rats. Endothelial Regrowth (mm) 2wks 3wits 4wks 12wks DM 2.1+/-1 3.5+/-.2 4.7+/-.3 5.9+/-.4 n=7 n=12 n=24 n=6 ND 2.4+/-.2 3.1+/-.1 4.8+/-.2 5.7+/-.8 n-16 n=23 n=37 n-6 Using a two tailed unpaired T test, there were no significant differences at the early times, but at the 12 week point, there was significantly less endothelial regrowth in the DM animals compared with the ND rats (p<0 012); however, no significant differences were noted in intimal thickening at any time point. Thus, the vascular response to injury in genetically inbred rats is not significantly influenced by insulin treated diabetes in this model. This suggests that increased restenosis following angioplasty in diabetic patients may be attributable to a longer period of diabetes or to other coexistent risk factors.