Relationship between the prevalence of anti-glutamic acid decarboxylase autoantibodies and duration of type 1 diabetes mellitus in Brazilian patients

Abstract

The objective of the present study was to determine whether the duration of disease has any influence on the prevalence of glutamic acid decarboxylase autoantibodies (GADA) in Brazilian patients with type 1 diabetes (T1D) and variable disease duration. We evaluated 83 patients with T1D. All participants were interviewed and blood was obtained for GADA measurement by a commercial radioimmunoassay (RSR Limited, Cardiff, UK). Four groups of patients were established according to disease duration: A) 1-5 years of disease (N = 24), B) 6-10 years of disease (N = 19), C) 11-15 years of disease (N = 25), and D) >15 years of disease (N = 15). GADA prevalence and its titers were determined in each group. GADA was positive in 38 patients (45.8%) and its frequency did not differ between the groups. The prevalence was 11/24 (45.8%), 8/19 (42.1%), 13/25 (52%), and 6/15 (40%) in groups A, B, C, and D, respectively (P = 0.874). Mean GADA titer was 12.54 ± 11.33 U/ml for the sample as a whole and 11. 95 ± 11.8, 12.85 ± 12.07, 10.57 ± 8.35, and 17.45 ± 16.1 U/ml for groups A, B, C, and D, respectively (P = 0.686). Sex, age at diagnosis or ethnic background had no significant effect on GADA (+) frequency. In conclusion, in this transversal study, duration of disease did not affect significantly the prevalence of GADA or its titers in patients with T1D after one year of diagnosis. This was the first study to report this finding in the Brazilian population.

Influence of age at diagnosis and duration of diabetes on the positivity of glutamic acid decarboxylase antibody in South-Brazilian type 1 diabetes mellitus

“…A recent study in Southern Brazil found 63% of GADA positivity in patients with type 1 DM duration between three and five years. 31 On the other hand, the study of Rodacki et al 32 described GADA positivity prevalence of 45.8% of type 1 diabetes patients with a mean duration of disease of 10 y, not affected by disease duration or age at diagnosis. The authors speculate that this low positivity may be due to the fact that only patients with more than one-year of diabetes duration were included in the analysis.…”

Persistence of islet autoantibodies after diagnosis in type 1 diabetes

“…Cross‐sectional studies from outside of Europe and North America generally support an effect of ethnicity on autoantibody prevalence, but large studies of populations of non‐European origin are required. Overall lower GADA and IA‐2A prevalence has been reported after diagnosis, compared with people of Northern European origins, for Tanzania, 41 the Philippines 42 and Taiwan, 43 but not for Brazil (GADA only) 44 . A lower ZnT8A prevalence has been reported South African populations 45 .…”

GAD65 antibody prevalence and association with c-peptide, HLA class II alleles in Beninese patients with type 1 diabetes

“…25 The Figure 1 shows that GAD65Ab remains detectable in blood long time after the diagnosis of type 1 diabetes with a peak of 100% observed after 6 years of T1D. Therefore, the investigation of GAD65Ab is very useful to identify the latent autoimmune diabetes cases in adult (LADA).…”