Insulin and Glucagon are pancreatic hormones that control sugar metabolism. Insulin is responsible for lowering the blood sugar level as it increases cellular uptake of glucose. Thus it transports glucose from the blood into the cells. In IDDM (Insulin dependent diabetes mellitus) the insulin production is impaired due to which glucose accumulates in the blood. This will increase the viscosity of blood and will hamper the blood flow. This condition can be corrected by intravenous insulin and thus insulin will directly enter the blood and thus reduce the blood sugar. Insulin cannot be given orally because insulin is proteinaceous hormone and proteins easily dissolve in the stomach.