INS and type 2 diabetes mellitus: There is a subtype of T2DM, ketosis-prone type 2 diabetes (KPD, also known as Flatbush diabetes or type 1.5 diabetes), that describes patients with impaired insulin secretion in response to severe hyperglycemia, lacking typical autoimmune markers of type 1 disease, and with quick recovery of β-cell function after resolution of DKA [8,9].