Abstract Body: Background: Type 2 diabetes mellitus (T2D) impairs capillary perfusion and exacerbates ischemic injury in deep brain regions in male but not female young adult mice. Male mice express higher level of soluble epoxide hydrolase (sEH) in cerebrovascular endothelium than females, which is further increased by T2D. Inhibition of sEH, which increases endothelial-derived vasoprotective epoxyeicosatrienoates (EETs), protects nondiabetic but not T2D male mice. We tested hypotheses that T2D worsens ischemic injury and capillary perfusion in males by mechanism(s) unrelated to endothelial sEH, but that premenopausal females are protected from T2D-related impairment in postischemic capillary perfusion and increased ischemic damage due to reduced endothelial sEH. Methods: T2D was induced in 9 months old male and female mice with overexpression of human sEH in endothelium (Tie2-hsEH) and wild-type littermates (WT). At 7 weeks’ treatment, mice were subjected to transient focal cerebral ischemia by intraluminal middle cerebral artery occlusion (MCAO) x 60 min. Capillary red blood cell (RBC) flux was measured 24-hour after reperfusion using high-resolution optical microangiography (OMAG), followed by measure of brain infarct size by H&E staining. Results: In nondiabetic male mice, striatal infarct size did not differ between WT and Tie2-hsEH mice, although Tie2hsEH genotype had 31% lower postischemic capillary flux (n=8 and 8; p<0.05). In contrast, infarct size for nondiabetic Tie2-hsEH female mice was 35% larger than in WT counterparts (n=6 and 10; p<0.05), accompanied 39% decreased postischemic capillary flux (n=6 and 10; p<0.05). T2D increased striatal infarct size in male WT and Tie2-hsEH mice, by 32% (n=9 and 7; p<0.01) and 33% (n=7 and 7; p<0.001), accompanied by lower postischemic capillary flux, by 32% (n=9 and 8; p<0.01) and 38% (n=7 and 8; p<0.05), resp., vs nondiabetic controls. In contrast, T2D did not alter infarct size or postischemic capillary flux in females, in either WT or Tie2hsEH mice. Conclusions: Endothelial sEH and EETs are critical factors underlying brain protection from diabetes-exacerbated ischemic injury in premenopausal female mice. In contrast, vulnerability of male mice to diabetes-exacerbated ischemic injury appears to involve mechanism(s) unrelated to endothelial sEH and EETs. Findings highlight potential for sEH inhibition as effective therapy for stroke in diabetic females but not males.