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

Abstract

Autoimmune pancreatitis (AIP) was first described in 1961 and accounts for 5-6% of cases of chronic pancreatitis, though the prevalence is increasing with increasing awareness of the disease1,2. There are two types of autoimmune pancreatitis with different clinical and pathological features. Type 1 AIP is an IgG4 related disease and tends to occur in elderly patients in the 7th decade, with a male preponderance3. Type 1 AIP is associated with other organ involvement and commonly affects the biliary system3. In contrast, Type 2 AIP occurs in patients in the 5th-6th decade of life and other organ involvement is uncommon3. Both types of AIP respond well to steroids with reported remission rates of 99% and 92% for Type 1 and Type 2 AIP respectively4. Case report: A 69-year-old man was referred to the diabetes clinic with poor glycaemic control despite escalation of oral hypoglycaemic therapy. He had been diagnosed with Type 2 diabetes mellitus (T2DM) 1 year previously, having presented with polyuria, one stone weight loss and a HbA1c of 12%. His past medical history included asthma, benign prostatic hypertrophy, treated hypertension, B12 deficiency and gallstone cholecystitis. At presentation to the diabetes clinic, his BMI was 24kg/m2 with a HbA1c of 8.1% on Gliclazide 120mg daily and Pioglitazone 15mg daily. A previous trial of Metformin and Saxagliptin had been ineffective at lowering blood glucose levels. He was commenced on Insulin Detemir once daily to optimise diabetes control. In view of the significant weight loss and hyperglycaemia despite multiple agents, computerised tomography (CT) of the pancreas was arranged. This revealed pancreatic duct dilatation within an atrophic pancreatic tail. Magnetic Resonance Cholangiopancreatography (MRCP) demonstrated a prominence in the pancreatic head and neck region which appeared malignant when further imaged with endoscopic ultrasound (EUS).