Is Latent Autoimmune Diabetes in Adults Distinct From Type 1 Diabetes or Just Type 1 Diabetes at an Older Age?

  1. Jerry P. Palmer12,
  2. Christiane S. Hampe1,
  3. Harvey Chiu12,
  4. Amit Goel12 and
  5. Barbara M. Brooks-Worrell12
  1. 1Department of Medicine, Division of Metabolism, Endocrinology and Nutrition, University of Washington, Seattle, Washington
  2. 2Department of Veterans Affairs Puget Sound Health Care System, Seattle, Washington
  1. Address correspondence and reprint requests to Jerry P. Palmer, MD, DVA Puget Sound Health Care System, Endocrinology (111), 1660 S. Columbian Way, Seattle, WA 98108. E-mail: jpp{at}u.washington.edu

Abstract

Diabetes is classified clinically into two types: type 1 and type 2 diabetes. Type 1 diabetes is an autoimmune diabetes, whereas, in contrast, type 2 diabetes is nonautoimmune. However, there is a group of phenotypic adult type 2 diabetic patients (∼10%) who have islet autoantibodies similar to type 1 diabetes. These patients are said to have latent autoimmune diabetes in adults (LADA) or type 1.5 diabetes. T-cells reacting with islet proteins have been demonstrated in type 1 and type 1.5 diabetic patients. In contrast, classic autoantibody-negative type 2 diabetic patients are also negative for T-cell responses to islet proteins. Therefore, we questioned whether type 1 and type 1.5 diabetes are similar or different autoimmune diseases. We have investigated the immunological and metabolic differences between type 1, type 1.5, and classic type 2 diabetic patients. We have identified autoantibody differences, differences in islet proteins recognized by T-cells, and differences in insulin resistance. We have also identified a small group of patients who have T-cells responsive to islet proteins but who are autoantibody negative. These patients appear to be similar to type 1.5 patients in having decreased stimulated C-peptide values. These immunological differences between type 1 and type 1.5 diabetes suggest at least partially distinct disease processes.

Footnotes

  • This article is based on a presentation at a symposium. The symposium and the publication of this article were made possible by an unrestricted educational grant from Servier.

    • Accepted April 28, 2005.
    • Received March 4, 2005.
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