Latent autoimmune diabetes in an adult patient presenting as suspected neuroendocrine tumour, Crohn's disease and malabsorption syndrome: A case report

Latent autoimmune diabetes in adults (LADA) is an autoimmune form of diabetes frequently misclassified as type 2 diabetes mellitus (T2DM), resulting in delayed insulin initiation and the progressive loss of β‑cells. The present case report describes the case of a 39‑year‑old man with long‑standing, severely uncontrolled diabetes who presented with hyperosmolar hyperglycaemic state (HHS), profound unintentional weight loss (113.4 to 57.2 kg over a period of 1 year), chronic watery diarrhoea and a pruritic vesicular rash. This constellation prompted an evaluation for neuroendocrine tumour, Crohn's disease, and malabsorption syndromes before the underlying autoimmune diabetes was recognised. Extensive infectious, malignant and gastrointestinal evaluations were unrevealing. Endocrine workup demonstrated positive glutamic acid decarboxylase (GAD‑65, 33 IU/ml; reference, <5), islet cell (1:8; reference, <1:4) and zinc transporter 8 (ZnT8, 20 U/ml; reference, <10) antibodies with severely reduced C‑peptide (0.12 nmol/l; reference, 0.26‑1.28), confirming LADA. He was managed with intravenous insulin for HHS and transitioned to neutral protamine Hagedorn (NPH) and regular insulin, with improved glycaemic control and partial symptom resolution. The present case report highlights the diagnostic challenges of LADA in adults presumed to have T2DM despite poor glycaemic control, and demonstrates that profound insulin deficiency can phenocopy malignancy and inflammatory bowel disease. Recognition through islet autoantibody and C‑peptide testing is essential for timely insulin initiation, which may limit hyperglycaemia, β‑cell decline and complications.