A Case of Autoimmune Pancreatitis Presenting as a Deterioration in Glycemic Control in a Patient with Pre-Existing Type 2 Diabetes

Abstract

The present article demonstrates an unusual case of type 1 autoimmune pancreatitis (AIP), focusing on the cause of deterioration in glycemic control and weight loss in a patient with pre-existing type 2 diabetes mellitus (DM). A 67-year-old man was diagnosed with type 2 DM 23 years prior and presented with weight loss of approximately 6 kg over a period of 3 months and hemoglobin A1c (HbA1c) of 9.1%. His carbohydrate antigen 19-9 (CA 19-9) level was elevated to 158.54 U/mL (normal, 0~37 U/mL). Considering these findings, we needed to rule out hidden malignancy. Computed tomography of the abdomen showed diffuse swelling of the pancreas uncinated process. The serum immunoglobulin G (IgG) level was elevated to 2,418 mg/dL (normal, 700~1,600 mg/dL), and IgG4 level was elevated to 1,115.0 mg/dL (normal range, 3.9~86.4 mg/dL). This case highlights that AIP should be considered as a cause of significant weight loss and a deterioration in glycemic control in patients with DM. Furthermore, a pancreatic imaging study should be considered in clinical practice to differentiate pancreatic cancer and AIP.