 This study is designed to investigate the effects of diabetes mellitus and its treatment upon the bodys responses to low blood glucose blood sugar levels. Diabetes is a medical condition in which blood glucose can rise very high. Treatment of diabetes mellitus involves giving insulin a hormone, which can occasionally cause blood glucose to fall too low. The body responds to low glucose levels by producing a number of hormones, which act against the insulin to help correct the low blood glucose. These hormones also provide symptoms which warn that the glucose is falling too far. These protective warnings by the body may be different in people with diabetes. We want to test whether this also means that diabetes changes the sensitivity of brain function to a lowering of blood glucose levels. In order to answer this question, we need to compare the response of people with diabetes with the response of people who do not have diabetes. 