Because selective serotonin reuptake inhibitors are commonly prescribed to treat depression, it is vital to understand how these antidepressants affect hypoglycemia- the most feared complication in diabetes. This study's aim is to determine whether individuals who are chronically taking selective serotonin reuptake inhibitors have a reduced ability to defend against hypoglycemia compared to individuals not taking the medication, thus leaving them more susceptible to hypoglycemia. Both healthy volunteers and volunteers with type 1 diabetes mellitus will be studied. The results could potentially be important to diabetic patients, by demonstrating to physicians how to modify therapy for those taking antidepressants in order to avoid hypoglycemia.