Optimal Cutoff Point of Glutamate Decarboxylase Antibody Titers in Differentiating Two Subtypes of Adult‐Onset Latent Autoimmune Diabetes

Abstract

The optimal cutoff point of glutamate decarboxylase antibody (GAD-Ab) titers for differentiating two latent autoimmune diabetes (LADA) subtypes remains unclear. One hundred and forty-five GAD-Ab-positive patients screened from phenotypic type 2 diabetes were diagnosed as LADA. The clinical features were compared among LADA patients with different GAD-Ab titers. The receiver-operating characteristic (ROC) curve was used to evaluate the diagnostic value of GAD-Ab titers and to define the optimal cutoff point. The heterogeneity of clinical features in LADA could be discriminated by five GAD-Ab titers, with maximal differences at the titer of 175 U/mL. The ROC curve analysis showed that the optimal cutoff point for discriminating two LADA subtypes was at the titer of 175 U/mL, with sensitivity and specificity of 54.5% and 92.1%, respectively. These findings demonstrated that the two clinically distinct subtypes of LADA can be optimally discriminated by the GAD-Ab titers.

High titre of antiglutamic acid decarboxylase autoantibody is a strong predictor of the development of thyroid autoimmunity in patients with type 1 diabetes and latent autoimmune diabetes in adults

“…LADA comprises a heterogeneous group. Patients with high levels of GADA have a more T1DM phenotype, but those with low levels display a phenotype closer to T2DM 19,21 . As expected from previous studies, 19,21 we observed a higher prevalence of thyroid antibodies in LADA patients with high GADA titres than those with low, which indicated that patients with LADA, especially those with high GADA titre, have a higher risk for thyroid autoimmunity and may be considered autoimmune polyendocrine syndrome type III.…”

“…Glutamic acid decarboxylase antibody and IA‐2A were determined by radioligand binding assays as previously described 21 . The cut‐off points of GADA and IA‐2A were 18·5 and 2·7 U/mL, respectively, determined according to the 99·5% upper limit of 188 and 171 healthy controls.…”

Variation of C peptide decay rate in diabetic patients with positive glutamic acid decarboxylase antibody: better discrimination with initial fasting C peptide

“…[7,8]. Previous studies reported that GAD-Ab titer could help identify the heterogeneity of LADA patients with LADA-type 1 and LADA-type 2 diabetes [9,10]. But for juvenile- and adult-onset autoimmune diabetes, the status and the titer of GAD-Ab is not so helpful [11].…”

Type 1 and Type 2 Diabetes

“…When subjects commencing permanent insulin treatment during the first year after diagnosis are excluded, ϳ50 -60% of LADA patients compared with 2% of antibody-negative patients develop marked insulin deficiency during the 6 -10 years from diagnosis (28,35). The progression of insulin deficiency seems to be associated with younger age at onset, high levels of GADAs, and positivity for multiple autoantibodies; this group may also have other endocrine autoantibodies (27,28,36,37). On the other hand, half of the patients with LADA will never need treatment with insulin and only have a mild deterioration of their maximal insulin secretory capacity compared with GADA Ϫ patients (38).…”