T3cD differs from traditional T1D or T2D in that it is often caused by exocrine pancreatic injury, such as infection, acute or chronic pancreatitis, trauma, or surgery resulting in reduction of islet cells; its main symptoms include hypoinsulinemia, hepatic insulin resistance, decreased pancreatic polypeptide levels, and increased peripheral insulin sensitivity. The gene discussed is PPY; the disease is chronic pancreatitis.