Clinical characteristics of anti-glutamic acid decarboxylase antibody-positive fulminant type 1 diabetes

This research aimed to examine the relationship between anti-glutamic acid decarboxylase antibody (GADA) titers and clinical parameters at onset and to clarify the association between clinical severity and GADA titers in GADA-positive fulminant type 1 diabetes. This cross-sectional observational study included 20 cases with GADA-positive fulminant type 1 diabetes (4 cases from our hospital and 16 from cases reported in the literature). The association between GADA titers and clinical parameters [age, sex, body weight, body mass index, period from appearance of any prodromal symptoms to diagnosis, period from development of hyperglycemic symptoms to diagnosis, GADA titer, HbA1c level, blood pH and HCO₃^- level, serum levels of ketone bodies and pancreatic exocrine enzymes] were analyzed. Spearman's rank correlation coefficient (r_s) was used for the correlation analysis. The results showed that there was a significant inverse correlation between GADA titers and the "period from appearance of any prodromal symptoms to diagnosis" (r_s = -0.559, p < 0.05). Moreover, GADA titers were inversely correlated with blood pH and HCO₃^- level (r_s = -0.576, p < 0.05, r_s = -0.578, p < 0.05, respectively), and positively correlated with serum levels of total ketone bodies, acetoacetate, and 3-hydroxybutyrate (r_s = 0.661, p < 0.05; r_s = 0.700, p < 0.05; and r_s = 0.782, p < 0.01, respectively). These findings suggest that higher GADA titers may be linked to more severe clinical severity of GADA-positive fulminant type 1 diabetes at onset. This association may be attributed to possible pre-existence of autoimmunity-related β-cell damage before the onset of fulminant type 1 diabetes.