Endocrine Abstracts

Background: There is increasing evidence of the role of diabetes autoantibody testing in the classification of less common types of diabetes. Patients with negative autoantibodies may warrant further investigation to ensure the correct diagnosis is reached.

Objectives: - To identify and characterise the population of patients <16yrs with triple autoantibody (GAD, IA2, ZnT8) negative diabetes in Lanarkshire.- To develop a new guideline for the management and investigation of these patients.

Methods: SCI Diabetes and Clinical Portal were reviewed for patient identification and data collection. Available literature and clinical guidance regarding autoantibody testing and associated investigations were reviewed and used to develop a local clinical pathway for the management of patients with negative autoantibody results.

Results: 15% of the clinic population <16yrs (41/320 patients) had no autoantibody results available. 17 patients (5%) were triple autoantibody negative. 8 patients had only one mildly positive antibody result and a further 15 had no positive antibody results but had not been fully tested. Of those with three negative antibodies, 1 had subsequently been diagnosed with MODY 2 and one had stopped insulin treatment but the diagnosis remained uncertain. There were no clear clinical or biochemical features suggestive of non-type 1 diabetes in these patients. 5 presented in DKA. 13/17 patients had C Peptide tested at diagnosis, with 6 (46%) <100 pmol/l. 3 patients had positive TPO antibodies, but none had other autoimmune diagnoses. 3 patients had a first degree relative with diabetes. Only 2 patients had genetic testing performed. A guideline and pathway was developed and implemented for further investigation of patients identified with triple negative autoantibodies and a single mildly positive antibody, including repeat C peptide testing and consideration of genetic testing. Antibody testing was planned for those without full antibody results available.

Discussion: Implementation of a local pathway for investigation of triple autoantibody negative patients has the potential to identify patients with less common diabetes diagnoses, and subsequently change their prognosis and management. We aim to review the outcome of the pathway and report any subsequent diagnostic change.