The purpose of this study is to determine whether diabetics have decreased amounts of oxygen in the skin compared to non-diabetic individuals, and if the amount of oxygen in the skin changes when given more oxygen to breathe around the time of surgery. To do this, the investigators will be measuring the amount of oxygen in the skin of diabetic and non-diabetic individuals who will be undergoing abdominal surgery lasting 2-4 hours. These measurements will be taken at three different times.