In response to high levels of glucose in the blood, the insulin-producing cells in the pancreas secrete the hormone insulin. Type I diabetes occurs when these cells are destroyed by the body's own immune system.
Review Date 1/26/2020
Updated by: Brent Wisse, MD, board certified in Metabolism/Endocrinology, Seattle, WA. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.