Background: Various metabolic aetiologies underpin the diagnosis of gestational diabetes (GDM) and influence an individual’s propensity for the subsequent development of diabetes. GDM could be considered a ‘stress test’ for the pancreatic beta cell. Antibody positivity in GDM may indicate less beta cell reserve and preclinical type 1 diabetes. Greater understanding of the clinical significance of positive antibodies in GDM may help clinicians identify ‘high risk’ individuals whom require closer surveillance post-partum.
Aims: To determine the prevalence, trajectory and clinical significance of diabetes-related autoantibodies in a multiethnic GDM population during pregnancy and post-partum.
Methods: We measured GAD, IA2 and insulin antibodies at diagnosis of GDM and 3 months post-partum. Antibody positivity was correlated with demographic data, maternal indices and fetal outcomes.
Results: We recruited 302 women with GDM. At this stage, 121 women have completed postnatal testing. The overall prevalence for antibody positivity in GDM was 5.6% during pregnancy and 10.7% post-partum (Table 1). None of the cohort had more than one positive antibody. With respect to individual antibody titres, GAD antibody and insulin antibody in insulin naïve patients remained stable between pregnancy and post-partum. IA2 antibody trended upwards post-partum (significant paired test) (Table 2).
There was no significant difference in demographic characteristics, antenatal OGTT results, insulin use, and pregnancy outcomes in antibody-positive compared with antibody-negative women.
Conclusions: The rising prevalence of diabetes-related antibodies from pregnancy to post-partum is consistent with the trajectory data for antibody titres and may reflect haemodilution or immunomodulation during pregnancy. A similar pattern has been reported for thyroid antibodies.1 Antibody positivity does not appear to correlate with antenatal glycaemic control, insulin treatment or perinatal outcome. The possibility that the presence of antibodies in GDM predicts earlier diabetes (type 1 or type 2) post-partum remains to be seen.