Relationship between serum glutamic acid decarboxylase antibody titer and the first-phase insulin release in newly-diagnosed type 2 diabetic patients

Abstract

To investigate the relationship between serum glutamic acid decarboxylase antibody (GAD-Ab)titer and the first-phase insulin release (1PH)in newly-diagnosed type 2 diabetic patients. 1053 newly-diagnosed type 2 diabetic patients were divided into 3 groups, including 71 individuals with GAD-Ab≥1 U/ml (positive group), 171 individuals with GAD-Ab ranging from 0 to 1 U/ml (negative-1 group), and 811 individuals with GAD-Ab=0 (negative-2 group). IPH was evaluated by arginine stimulation test. In the patients of negative-2, negative-1, and positive groups, the respective values of 1 PH were subsequently decreased significantly (P< 0. 01) , and the detection rates of the decreased insulin secretion were 74. 85%, 87. 13%, and 100%, respectively. Stepwise regression analysis indicated that disease duration, GAD-Ab titer, HbA_1C, and body mass index were the major independent contributing factors. The titer of GAD-Ab has an important impact on 1PH defect in type 2 diabetic patient. Detection of GAD-Ab not only provides an evidence for clinical type, but would also be helpful in determining the islet β-cell function. Key words: Diabetes mellitus; Glutamic acid decarboxylase antibody; Arginine stimulation test