Study B. Intranasal glucagon (glucagon, Eli Lilly, Canada) administration with measurement of endogenous glucose production under pancreatic clamp conditions Each study participant will be admitted to the Metabolic Test Centre of the Toronto General Hospital the day before the study at 12pm. They will be provided with a standardized dinner (consisting of 7 Kcal/kg; 50% carbohydrate, 30% fat, and 20% protein) and will then be required to fast for 12 hr overnight (can have water but no other food or drinks).