Clinical Characteristics of GADA-Positive Patients with Diabetes and the Role of GAD Antibody Assay to Reclassify the Diagnosis in a Limited Resource Setting

Abstract

Patients with diagnosis of T2DM may also have islet antibodies typically associated with T1DM, as Latent Autoimmune Diabetes of the Adult (LADA). More than 90% of LADA patients in have antibodies against Glutamic Acid Decarboxylase (GADA). Prevalence of LADA is between 4% and 12% of all adults with a clinical T2D phenotype. T1DM in a limited resource setting is generally diagnosed based mainly on clinical features which may lead to misclassified diagnosis. We utilised GAD antibody assay to reassess the challenging referred cases in our speciality centre by biochemical evaluation. We explore the clinical characteristics one-year post diagnosis of T1DM to reclassify the diagnosis in 20 patients (males = 15, females = 5). The complications reported at the time of diagnosis were, peripheral neuropathy (n=3), hypoglycaemia (n=2), peripheral vascular disease (n=1) and amputation of both toes (n=1). Five patients reported positive family history. Mean age (years) 33 ± 8.4, 95% CI 29 - 37, min 18, max 55. Mean levels of HbA1c (%) was 11 ± 3.1, 95% CI 9.6 - 13, min 7.4, max 17. Mean levels of GAD antibody (IU /ml) was 50 ± 84, 95% CI 11 - 90, min 3.6, max 255. Patients were categorised into subgroups by GADA status, GADA low: ≤ 200 IU ml (n=, GADA high: > 200 IU/ml. Three patients reported high GADA levels of which two were males and one female and two reported complications as amputation and hypoglycaemia. Following reclassification, nine patients were re-diagnosed as T2DM with the management plan shifted from primarily insulin based regimen to oral antidiabetics approach. Two patients each were re-diagnosed as Maturity Onset Diabetes of the Young (MODY) and early onset T2DM. Our study highlights the importance of GAD antibody assay for an early precise diagnosis in a limited resource setting. Disclosure P.J. Goswami: None. B.D. Saboo: None. K.K. Patel: None. B.N. Patel: None. N. Wadhwa: None.