PTPRN and diabetes mellitus: According to the American Diabetes Association, T1DM can be broadly classified into two forms: (a) type 1A is usually characterized by the presence of antibodies against host proteins such as insulin, heat shock protein 60, insulinoma associated proteins (IA-2) and glutamic acid decarboxylase (GAD65) and (b) type 1B which is less frequent and has no known cause.