The purpose of this study is to better understand the effect of low blood sugar (hypoglycemia) on blood flow and biochemistry in the brain. Hypoglycemia is a serious complication of diabetes treatments. It has been previously observed that hypoglycemia causes an increase in blood flow to certain parts of the brain, but it has been difficult to determine which parts of the brain specifically have an increase in blood flow. With new technology, it is now possible to determine the rate of blood flow in very small parts of the brain. The investigator expects that people with type 1 diabetes and hypoglycemia unawareness, poorly controlled diabetes, and normal subjects will have different rates of blood flow to different parts of the brain in response to hypoglycemia. Having a greater understanding of how the brain adapts to hypoglycemia may help us develop better ways to treat diabetes more safely.