INS and diabetes mellitus: The present data demonstrated that islets of diabetes-resistant and diabetes-prone mouse strains respond inversely to a glucose challenge: In B6-ob/ob islets, the induction of proliferation resulted in a strong increase in beta-cell mass, which appears to be responsible for an increase in plasma insulin concentration and a sufficient control of blood glucose even under glucotoxic conditions, whereas NZO islets lack the ability to initiate cell cycle progression and to maintain the survival pathway.