Diagnostic value of carboxypeptidase-H autoantibodies in detecting latent autoimmune diabetes in adults.

Abstract

Objective: To investigate the diagnostic value of carboxypeptidase-H (CPH) autoantibodies in Chinese patients with the latent autoimmune diabetes in adults (LADA).

Methods: One hundred and fifty-four Type 1 diabetes, 104 Type 2 diabetes, and 144 healthy people were enrolled. Recombinant human CPH (54 kD) was labeled by in vitro translation with 35S-methionine and used to evaluate autoantibodies to CPH (CPH-Ab). Radioimmunoassay was applied to detect antibodies to glutamic acid decarboxylase (GAD-Ab), intracellular part of protein tyrosine phosphatase-like protein (IA2ic-Ab), and autoantibodies to insulin (IAA).

Results: No differences in CPH-Ab prevalence were found among Type 1 diabetic patients (5/154, 3.2%), Type 2 diabetic subjects (6/104, 5.7%),and the healthy controls (3/144, 2.1%). The prevalences of GAD-Ab, IA2ic-Ab, and IAA were 15.4% (16/104), 2.9% (3/104), and 2.3% (1/43), respectively in Type 2 diabetes. All IA2ic-Ab or IAA-positive patients with Type 2 diabetes were GAD-Ab-positive. No GAD-Ab- or IAA-positive subjects were observed in CPH-Ab-positive patients with Type 2 diabetes.

Conclusion: CPH-Ab may provide some diagnostic value for LADA, and improve the sensitivity in diagnosing LADA in Chinese when combined with GAD-Ab test in Type 2 diabetes.