Animal Models of Type 1 and Type 2 Diabetes Mellitus

Diabetes mellitus is a group of diseases characterized by hyperglycemia due to a relative or complete deficiency of the hormone insulin. There are two main categorizations of diabetes: Type 1 diabetes which is caused by autoimmune destruction of the beta cells and Type 2 diabetes which is caused by an inability of beta cells to compensate for insulin resistance. The pathogenesis of each is distinct and animal models should reflect this. In animal models of Type 1 diabetes, beta cell ablation is a common characteristic. This can be achieved using spontaneous models of autoimmune diabetes or alternatively beta cells can be depleted by chemical means. Type 2 diabetes is closely associated with obesity, which is a condition in which insulin resistance is prevalent. Thus many models have an obese and insulin resistant phenotype but a key characteristic for animals to develop overt Type 2 diabetes is the inability of beta cells to compensate to an increased insulin demand.