[Genetic, endocrine, drug-induced and pancreatogenic forms of diabetes and exocrine pancreatic insufficiency (Update 2026)].

Diabetes classified as category 3, usually referred to as type 3 diabetes, encompasses specific types due to other causes. These specific forms of diabetes are clinically and pathophysiologically very heterogeneous. Type 3 diabetes encompasses inherited forms of diabetes (monogenetic diabetes, neonatal diabetes, Down syndrome, Klinefelter syndrome, Turner syndrome), diabetes due to other endocrine disorders (acromegaly, Cushing's disease, glucagonoma) and drug-induced forms, e.g., caused by glucocorticoids, immune checkpoint inhibitors, calcineurin inhibitors, phosphatidylinositol 3 kinase inhibitors, highly active antiretroviral therapy (HAART) and antipsychotics. Additionally, this category includes pancreatogenic forms (after pancreatic surgery, after pancreatitis, pancreatic tumors, hemochromatosis, cystic fibrosis), rare infection-triggered (e.g., congenital rubella syndrome) and autoimmune forms other than type 1 diabetes (e.g., Stiffman syndrome, anti-insulin receptor antibodies, insulin autoimmune syndrome). An exact diagnosis is critical for correct and optimal treatment of affected patients. Exocrine pancreatic insufficiency is not only found in patients with pancreatogenic diabetes but also in patients with type 1 diabetes or long-standing type 2 diabetes.