[Islet beta cell function in latent autoimmune diabetes in adults with islet cell antibodies].

Objective: To explore the predictive value and influence of islet cell antibody (ICA) and glutamic acid decarboxylase antibody (GAD-Ab) for beta cell function in latent autoimmune diabetes in adults (LADA) patients.

Methods: Fifty-six patients with initially diagnosed type 2 diabetes (including 10 cases of GAD-Ab-positive alone, 14 ICA-positive alone, 7 GAD-Ab and ICA-positive and 25 GAD-Ab and ICA negative) were followed up every 6 months (except the 2nd year) until the 5th year. Their fasting and postprandial C-peptide and glycemic control were measured. GAD-Ab was determined by radioimmunoprecipitation assay and ICA by ELISA kit.

Results: Decreased fasting C-peptide was found in patients with GAD-Ab alone and patients with GAD-Ab and ICA in the 2.5th year and to the end of the follow-up. The percentage of patients whose C-peptide decreased 50% or more compared with the baseline in the above 2 groups reached 60.0% in the 3nd year and 71.4% in the 3.5th year, respectively. No changes of the above parameters were found in ICA-positive alone group and GAD-Ab and ICA negative group. Complete beta-cell failure was found in 4 of the 10 patients in GAD-Ab alone group and in 1 of the 10 patients in ICA and GAD-Ab positive group. The number of failure patients in GAD-Ab alone group was more than that of the other 2 groups (P < 0.05 in both groups). There was no significant correlation between ICA index and FCP. Multiple stepwise regression analysis demonstrated that GAD-Ab contributed much more to FCP than ICA did.

Conclusion: The islet beta cell function decreases more quickly in GAD-Ab positive LADA patients than in ICA positive ones. The titer of GAD-Ab is an important prognostic factor in islet beta cell function, and the presentation of ICA-positive alone can not predict beta cell function in LADA patients.