The purpose of this study is to determine the way by which Alprazolam (Xanax) an anti-anxiety drug affects specialized molecules in your brain called GABA (A) receptors that alter your body's ability to defend itself from low blood sugar (hypoglycemia). We hypothesize that prior activation of GABA (A) receptors may result in blunting of counterregulatory responses during subsequent hypoglycemia and exercise.