Clinical Significance of Serum Anti-GAD65 Titer in Patients with Schizophrenia and Type2 Diabetes Mellitus

Background Schizophrenia is correlated to elevated incidence of type2 diabetes mellitus (T2D). Autoimmune responses targeting glutamate decarboxylase (GAD) may contribute to neurological disorders and diabetes development. Accordingly, the purpose of this research was to evaluate the clinical relevance of serum anti-GAD65 antibody levels in patients with schizophrenia and T2D, compared with healthy persons, T2D patients, and patients with schizophrenia. Methods This study involved 30 control subjects, 30 T2D patients and 60 patients with schizophrenia (30 patients with T2D and 30 patients without T2D). Levels of HbA1C with random blood sugar (RBS) were carried using commercial kits. Level of serum antiGAD65 antibodies was measured by using ELISA BioVendor GAD65 Assay Kit. Results When compared to controls, T2D patients, or even patients with schizophrenia, the data showed substantial (p < 0.05) increases in HbA1C, RBS, and BMI among schizophrenia patients with T2D. Serum antiGAD65 antibody titer elevated in patients with schizophrenia and T2D (237.33 ± 9.49, p < 0.001) when compared by controls (8.02 ± 0.28), T2D patients (31.39 ± 0.79) or even patients with schizophrenia alone (193.11 ± 8.12), in females when compared with males of all groups, and in patients with schizophrenia (either with or without T2D) who received Olanzapine than those who received Clozapine. Additionally, the findings of the ROC curve showed that, with an AUC of 0.736, a cut-off value of 212.5 IU/ml, 73.3% sensitivity, and 70% specificity, it was a promising prognostic biomarker that could predict T2D in patients with schizophrenia. Conclusion Serum AntiGAD65 titer is reliable prognostic biomarkers for predicting T2D in patients with schizophrenia.