[Immunological characteristics and islet function in first-degree relatives of latent autoimmune diabetes in adults]

To investigate the immunological features and pancreatic beta cell function of first-degree relatives of latent autoimmune diabetes in adults (LADA).

Oral glucose tolerance test (OGTT) was performed in 209 first-degree relatives of LADA patients and 340 first-degree relatives of classic T1DM patients. Radioligand assay was used to detect glutamic acid decarboxylase antibody (GADAb) and protein tyrosine phosphatase antibody (IA-2Ab). Intravenous glucose tolerance tests were performed in 39 normal controls and 46 first-degree relatives. Among them, 9 were GAD-Ab positive and 9 GAD-Ab negative first-degree relatives of patients with LADA while 12 were GAD-Ab positive and 16 GAD-Ab negative first-degree relatives of patients with classic T1DM.

(1) Immunological characteristics of first-degree relatives of patients with LADA. Similar with the first-degree relatives of patients with classic T1DM (18/340, 5.3%), the detection rate of GAD-Ab was 4.3% (9/209) in first-degree relatives of patients with LADA. (2) Islet function of first-degree relatives of patients with LADA. Compared with the control group, the first phase insulin release and the first phase insulin peak secretion averages were lower in the antibody positive group of first-degree relatives of patients with LADA (P < 0.05); HOMA-IR was higher in the antibody negative group of first-degree relatives of patients with LADA (P < 0.05). (3) Analysis on glucose metabolism of different immune status for first-degree relatives of patients with LADA. (1) The detection rate of impaired glucose tolerance (IGT) was 16.7% (35/209) and diabetes (DM) rate 10.0% (21/209). (2) The detection rate of IGT was higher in the antibody positive group than the antibody negative group in first-degree relatives of patients with LADA (37.5% vs 15.0%, P < 0.05).

Among first-degree relatives of patients with LADA, a certain extent of islet autoimmune antibody markers could be measured, and insulin resistance and insulin secretion defects were detected. The rate of IGT was higher in the antibody positive group than the antibody negative group.