It turned out that preoperative hyperglycemia, regardless of whether the patients received preoperative insulin medication, was associated with an elevated risk of perioperative ischemic stroke (OR: 1.55; 95% CI: 1.01–2.4; p = 0.047; OR: 2.25; 95% CI: 1.26–3.99; p = 0.006; respectively). This evidence concerns the gene INS and ischemic stroke.