Much of our present knowledge concerning the etiopathogenesis, treatment and prevention of human diabetes would never have been acquired without the study of animal models of diabetes. The main models of IDDM may be divided into two groups: induced (through pancreatectomy, chemicals such as alloxan and streptozotocin, viruses and others) and spontaneous (mainly using BB rats and NOD mice). The latter, at different ages, develop a diabetic syndrome, with clinical characteristics, genetics and immunology that are very similar to the human disease. Among the more significant differences are lymphopenia (in BB rats) and the predominance of diabetes in females (in NOD mice). Studies aimed at preventing IDDM have advanced by leaps and bounds by using the two spontaneous models. These include various methods such as genomic modification, an influence over some environmental agents, immunosuppression, immunotherapy, immunomodulation and tolerance induction as well as protection of the beta-cell from autoimmune attack. The conclusions drawn from animal experiments have allowed some human trials to be carried out with encouraging results.