| Noun | 1. | type I diabetes - severe diabetes mellitus with an early onset; characterized by polyuria and excessive thirst and increased appetite and weight loss and episodic ketoacidosis; diet and insulin injections are required to control the diseasediabetes mellitus, DM - diabetes caused by a relative or absolute deficiency of insulin and characterized by polyuria; "when doctors say `diabetes' they usually mean `diabetes mellitus'" autoimmune disease, autoimmune disorder - any of a large group of diseases characterized by abnormal functioning of the immune system that causes your immune system to produce antibodies against your own tissues | |