We propose a prospective case-control study which will include 30 Type II diabetics matched for age, sex, and race to 30 non-diabetic controls. Patients will be preselected from a population undergoing abdominal surgery and given supplemental inspired oxygen of 30 - 80% to PaO2 of approximately 150mmHg and/or 300mmHg at three timepoints in the perioperative period. PsqO2 will be measured with an IV-sized probe inserted through a small incision made in the skin. Data will be recorded and analyzed using unpaired two tailed t-test, Wilcoxon's ranked sum test, or repeated-measures analysis of variance (ANOVA) test as appropriate.