Interestingly, in contrast to the current belief that insulin insufficiency in CFRD is mainly due to destruction of the pancreatic islets6, our H&E examination revealed no significant difference in pancreatic islet morphology between CFTR wild-type and DF508 mice (Supplementary Fig. 7), indicating that the observed defect in insulin secretion in CF may not be caused by structural alteration of the islets. Here, INS is linked to cystic fibrosis.