Goto-kakizaki Rats: Its Suitability as Non-obese Diabetic Animal Model for Spontaneous Type 2 Diabetes Mellitus

β-cell dysfunction and apoptosis are recognized as a major cause of insufficient insulin secretion in response to high blood glucose and metabolic demand. As a consequence, type 2 diabetes mellitus (T2DM) is known to occur. Taking into account the etiology of T2DM, to conduct investigational studies directly on human diabetic patients seems to be unsuitable; thereby, various animal models have been established to investigate the pathogenesis of T2DM. Among these models, Goto-Kakizaki (GK) rats have been considered as one of the best non-obese type 2 diabetic animal model. GK rats exhibit valuable characteristic tools that are more or less common and functionally present in human diabetic patients. This animal model is considered appropriate to inspect various pathologic mechanisms of T2DM. Thereby, in our present article, we have comprehensively summarized the information relating the characteristics of abnormalities including a description of assorted mechanisms involved in pathogenesis of T2DM in GK rats. This might help to investigate various aspects of spontaneous T2DM.