Learn more about insulin here:

Review Basic Concepts in Diabetes

Role of Medical Therapy in Diabetes

Insulin Therapy in Diabetes

Managing Your Insulin and Medications

Fine tune Your Insulin Therapy

Recent Advances in Insulin Therapy including inhalable insulin (Exubura)

Overview:
Insulin is a hormone produced by an organ called the pancreas. Insulin helps move a sugar called glucose from the blood vessels into the body's cells for use as energy. Diabetes occurs when the body cannot make or respond to insulin and glucose builds up in the blood. High blood glucose can injure the kidneys, eyes, blood vessels and other parts of the body.
People with type 1 diabetes and some people with type 2 diabetes must administer insulin to themselves daily. Methods of administration include syringe injections, insulin pumps and insulin pens.