Article

Identification of Autoantibody-Negative Autoimmune Type 2 Diabetic Patients

Department of Medicine, University of Washington, Seattle, Washington, USA.
Diabetes care (Impact Factor: 8.57). 01/2011; 34(1):168-73. DOI: 10.2337/dc10-0579
Source: PubMed

ABSTRACT Islet autoimmunity has long been recognized in the pathogenesis of type 1 diabetes and is becoming increasingly acknowledged as a component in the pathogenesis of type 2 diabetes. Islet reactive T cells and autoantibodies have been demonstrated in type 1 diabetes, whereas islet autoimmunity in type 2 diabetes has been limited to islet autoantibodies. In this study, we investigated whether islet reactive T cells might also be present in type 2 diabetic patients and how islet reactive T cells correlate with β-cell function.
Adult phenotypic type 2 diabetic patients (n = 36) were screened for islet reactive T-cell responses using cellular immunoblotting and five islet autoantibodies (islet cell antibody, GADA, insulin autoantibody, insulinoma-associated protein-2 autoantibody, and zinc transporter autoantibody).
We identified four subgroups of adult phenotypic type 2 diabetic patients based on their immunological status (Ab(-)T(-), Ab(+)T(-), Ab(-)T(+), and Ab(+)T(+)). The Ab(-)T(+) type 2 diabetic patients demonstrated T-cell responses similar to those of the Ab(+)T(+) type 2 diabetic patients. Data were adjusted for BMI, insulin resistance, and duration of diabetes. Significant differences (P < 0.02) were observed among groups for fasting and glucagon-stimulated C-peptide responses. T-cell responses to islet proteins were also demonstrated to fluctuate less than autoantibody responses.
We have identified a group of adult autoimmune phenotypic type 2 diabetic patients who are Ab(-)T(+) and thus would not be detected using autoantibody testing alone. We conclude that islet autoimmunity may be more prevalent in adult phenotypic type 2 diabetic patients than previously estimated.

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