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Diabetes and Vascular Disease

MON-561 - Autoimmune Diabetes Following Recurrent Pancreatitis: An Unusual Overlap of Type 1 and Type 3C Diabetes

Monday, June 15, 2026
9:00 AM - 2:00 PM CT
Location: ENDOExpo; Poster Floor
Disclosure(s):
Punerdeep S. Sidhu, MD: No financial relationships to disclose
Jacqueline Silvia Martins Torrontegui, MD: No financial relationships to disclose
Aseel Abualnil, MD: No financial relationships to disclose
Ibrahim Hamad, MD: No financial relationships to disclose


Introduction:
Diabetes mellitus is categorized as type 1 diabetes mellitus (T1DM), an autoimmune disorder commonly associated with glutamic acid decarboxylase (GAD) antibodies, and type 2 diabetes mellitus (T2DM), characterized by insulin resistance with β-cell dysfunction. Type 3c (pancreatogenic) diabetes mellitus is a less recognized subtype resulting from pancreatic disease, most commonly chronic pancreatitis leading to irreversible pancreatic injury; however, its coexistence with autoimmune T1DM is rare and may lead to diagnostic ambiguity. Failure to classify diabetes type in patients with pancreatic disease can delay initiation of optimal therapy and increase the risk of metabolic decompensation. This case highlights chronic pancreatitis as a potentially overlooked clinical clue to autoimmune diabetes mellitus in a young adult.

Case Report:
A 24-year-old woman with prior episodes of recurrent idiopathic acute pancreatitis was recently diagnosed with diabetes (HbA1c 15%) and started on metformin without subtype determination. She was lost to follow-up after relocating. The patient presented with a painful erythematous mid–upper back mass. CT revealed a 2.5-cm abscess, managed with incision, drainage and antibiotics. Her course was complicated by hypotension and lactic acidosis (5.2 mmol/L), requiring ICU care for presumed septic shock; norepinephrine stabilized her, and she was later transferred to the floor. On admission, she was in diabetic ketoacidosis (HbA1c 14.6%) in the setting of infection requiring insulin infusion followed by basal–bolus therapy once clinically stable. Despite metformin adherence, she reported a 100-lb unintentional weight loss, steatorrhea, and frequent postprandial bowel movements, suggesting chronic pancreatitis with exocrine insufficiency. Autoimmune testing revealed markedly elevated GAD-65 antibodies (>250 U/mL) with negative zinc transporter 8 antibody, confirming autoimmune diabetes in the setting of underlying pancreatic disease.

Discussion:
Type 3c diabetes is usually antibody-negative. Although GAD antibodies are typical of type 1 diabetes and usually < 100 U/mL, our patient had markedly elevated levels (>250 U/mL), an unusual finding in pancreatitis-associated diabetes. Rare reports have described similarly elevated GAD titers following recurrent pancreatitis, suggesting a possible pancreatitis-mediated autoimmune process from immune exposure to pancreatic antigens during episodes of acute pancreatitis. Accurate differentiation between type 3c diabetes and autoimmune diabetes is critical for individualized treatment plan. Recognition of overlap phenotypes as in our patient is critical to guide appropriate therapy and avoid misclassification as these patients require more insulin, need early insulin initiation, and are at greater risk for severe hypoglycemia or diabetic ketoacidosis.

*Unless otherwise noted, all abstracts presented at ENDO must not be released to the press or the public until the date and time of presentation. For oral presentations, the abstracts are embargoed until the session begins. The Endocrine Society reserves the right to lift the embargo on specific abstracts that are selected for promotion prior to or during ENDO.*