Endocrine Abstracts

Introduction: Pancreatogenic diabetes (Type 3c diabetes-T3cDM) is rare in children, and frequently underdiagnosed. The prevalence is 5–10% of all adult diabetes cases in the developed world. Over 78% of people with T3cDM have chronic pancreatitis.

Case: A 15-year old presented with polyuria, polydipsia, abdominal pain, weight loss (WL) and a three-generational family history of type-1 (T1DM) and type-2 diabetes mellitus (T2DM). Examination revealed mild epigastric tenderness, with moderate dehydration. Bloods showed high blood glucose (BG):18.8 mmol/L (NR: 4–7) and HbA1C: 90mmol/mol (NR: 20–42). Blood ketones were negative. Serum amylase was 185 IU/L (NR: 25–125). Further tests including diabetes autoantibodies: Islet cell, Islet antigen 2, Glutamic acid decarboxylase- were negative and OGTT results showed a 2-hour BG of 18.8 mmol/l; and c-peptide of 498pmol/L. The results confirmed diabetes but not conclusive of either T1DM or T2DM. Next generation sequencing for all known monogenic diabetes genes was negative, hence excluding genetic maturity onset diabetes of the young (MODY). He was started on subcutaneous insulin (Glargine and NovoRapid). Over several weeks he complained of on-going abdominal pain, WL (8 kg over 6 weeks) and early satiety. A repeat amylase was very high (415 IU/l) and an abdominal MRI revealed a large pancreatic pseudocyst with pancreatic duct disruption, confirming diabetes secondary to chronic pancreatitis, also referred to as type-3c diabetes mellitus (T3cDM). Following bloods for fat soluble vitamins (A, D and E) he was commenced on vitamin D supplementation. His clotting profile was normal. After endoscopic drainage of the pseudocyst his abdominal symptoms resolved, however he remains on insulin therapy. Genetic tests for idiopathic pancreatitis (SPINK1 and PRSS1 genes) were negative.

Discussion and learning points: T3cDM is often mis-diagnosed as T2DM.The pathophysiology is pancreatic inflammation and destruction of islet cells. It is often complicated by malabsorption and malnutrition, and patients with T3cDM require insulin therapy more urgently than those with T2DM. Making the correct diagnosis is important for managing both exocrine and endocrine pancreatic insufficiency. Avoiding alcohol and smoking will reduce pancreatic inflammation. Early pancreatic imaging is recommended in suspected cases.