The main aim of the present review is to draw attention to the perturbations of D-fructose metabolism and insulinotropic action found in experimental models of dysfunction in insulin-producing cells. The first series of investigation was conducted in pancreatic islets of Goto-Kakizaki rats, an animal model of inherited type 2 diabetes. The second set of experiments deals with a comparable study performed on pancreatic islets from adult rats that had been injected with streptozotocin during the neonatal period, i.e. another current model of type 2 diabetes. Finally, the findings recorded in tumoral islet cells of the RINm5F line are presented.