Islet cell antibodies and glutamic acid decarboxylase antibodies, but not the clinical phenotype, help to identify type 1[frac12] diabetes in patients presenting with type 2 diabetes

• Published in: Metabolism, clinical and experimental clinical and experimental, 2001-09, Vol.50 (9), p.1008-1013
• Main Authors: Juneja, Rattan, Hirsch, Irl B., Naik, Ramachandra G., Brooks-Worrell, Barbara M., Greenbaum, Carla J., Palmer, Jerry P.
• Format: Article
• Language: English
• Subjects: Adult; African Continental Ancestry Group; Age Factors; Aged; Asian Continental Ancestry Group; Autoantibodies - blood; Autoantibodies - classification; Body Mass Index; Diabetes Mellitus, Type 1 - blood; Diabetes Mellitus, Type 1 - diagnosis; Diabetes Mellitus, Type 1 - immunology; Diabetes Mellitus, Type 2 - diagnosis; Diabetes Mellitus, Type 2 - immunology; Diagnosis, Differential; European Continental Ancestry Group; Female; Glutamate Decarboxylase - immunology; Humans; Hyperglycemia - etiology; Insulin - immunology; Isoenzymes - immunology; Male; Middle Aged; Phenotype; Polyuria - etiology; Predictive Value of Tests
• ISSN: 0026-0495; 1532-8600
• DOI: 10.1053/meta.2001.25654

This study was undertaken to determine which type 1 diabetes-associated autoantibodies and what clinical characteristics are most useful to identify patients with type 1[frac12] diabetes. We studied 125 patients, recently diagnosed clinically with type 2 diabetes for the presence of islet cell antibodies (ICA), insulin autoantibodies (IAA), antibodies to glutamic acid decarboxylase(GADAb), and IA-2a (IA-2Ab). Patients with a diagnosis of type 2 diabetes who met all of the following criteria at diagnosis were studied: age [ge ] 30 years, no history of ketonuria or ketoacidosis, and not requiring insulin treatment. Thirty-six patients (29%) were positive for at least 1 antibody. Thirty-two (26%) were ICA positive and 20 (16%) GADAb positive. Insulin autoantibodies and IA-2Ab occurred less frequently in 2 (1.6%) and 8 (6.4%) patients, respectively. There was no significant difference in the ages at diagnosis between the Ab(+) and Ab([minus ]) patients, age in years (range) 47.2 (32 to 64) versus 51.2 (31 to 77), respectively, P = .06. Body mass index (BMI) was different in the 2 groups, with Ab(+) patients being less obese, BMI (range) 28.3 kg/m 2 (17.6 to 54.9) versus 32.0 kg/m 2 (19.2 to 68.8), respectively, P = .01. Clinical presentation of diabetes was more commonly symptomatic with polyuria and polydipsia in Ab(+) patients, while in Ab([minus ]) patients, diagnosis was more often incidental, P = .002. However, more than 95% of patients overlapped in both age and BMI irrespective of antibody status. Similarly, 42% of Ab(+) patients had their diabetes diagnosed incidentally, while 29% of Ab([minus ]) patients presented with polyuria and polydipsia. We therefore conclude that screening with antibodies, mainly ICA and GAD, but not age, BMI, or clinical presentation should be used to identify type 1[frac12] diabetes.