INS and cystic fibrosis: CFTR in the regulation of insulin secretion and β cell function has also been reported as the mechanism of CFRD by several recent studies (Stalvey et al., 2006; Edlund et al., 2014; Guo et al., 2014; Fontes et al., 2015), which cannot fully explain the impaired insulin responses and glucose homeostasis reported in CF patients.