INS and diabetes mellitus: First, we examined diabetes-induced morphological differences in pancreas between the control and diabetic rats by immunofluorescence (IF) staining with tissue-specific cell surface markers (Figure 2), which revealed that the pancreatic islets of normal ZL rats had regular morphology and clear boundaries, the α cells secreting glucagon were distributed uniformly around the islets, the population of β cells was normal and distributed in the center of the islets, and the level of insulin secretion was higher (Figure 2A).