KIMURA, K., TOYOTA, T., KAKIZAKI, M., KUDO, M., TAKEBE, K. and GOTO, Y. Impaired Insulin Secretion in the Spontaneous Diabetes Rats. Tohoku J. exp. Med., 1982, 137 (4), 453-459 - Dynamics of insulin and glucagon secretion were investigated by using a new model of spontaneous diabetes rats produced by the repetition of selective breeding in our laboratories. The perfusion experiments of the pancreas showed that the early phase of insulin secretion to continuous stimulation with glucose was specifically impaired, although the response of the early phase to arginine was preserved. The glucose-induced insulin secretion in the nineth generation (F8) which had a more remarkably impaired glucose tolerance was more reduced than in the sixth generation (F5). No significant difference of glucagon secretion in response to arginine or norepinephrine was noted between the diabetes rats and control ones. The present data indicate that the defective insulin secretion is a primary derangement in a diabetic state of the spontaneous diabetes rats. This defect in the early phase of glucose-induced insulin secretion suggests the specific impairment of the recognition of glucose by the pancreatic β-cells. The spontaneous diabetes rats are very useful as a model of a disease for investigating pathophysiology of non-insulin dependent diabetes mellitus.