IAPP and type 2 diabetes mellitus: The significance of the found reduction in IAPP and IAPPO-IgA levels after 3 months of the O-BN diet should further be viewed from the notion that abnormal IAPP secretion and circulation of IAPP oligomers in T2D patients is associated with IAPP deposition and cell toxicity, which potentially contribute to diabetic complications (such as neuropathy, retinopathy, and vascular complications) found in these patients.