Abstract
AIM: To investigate the effects of the interaction between glycated haemoglobin (HbA1c) genetic risk score and weight changes during and after pregnancy (postpartum weight reduction and gestational weight gain) on long-term glycaemic changes in the largest cohort of women with a history of gestational diabetes mellitus (GDM). METHODS: This was a retrospective cohort using the baseline data from the Tianjin Gestational Diabetes Mellitus Prevention Programme. A genetic risk score was established by combining 10 HbA1c-related single-nucleotide polymorphisms, which were identified by genome-wide association studies. General linear regression models were applied to evaluate the effect of interaction between HbA1c genetic risk score and weight changes during and after pregnancy (postpartum weight reduction and gestational weight gain) on glycaemic changes. RESULTS: 'A total of 1156 women with a history of GDM were included in this respective cohort study. Statistical differences in pre-pregnancy weight, pre-delivery weight and postpartum weight were evidenced across different groups of postpartum weight reduction. After adjusting for covariates, statistical significance for changes in HbA1c level was only observed in the postpartum weight reduction <5 kg/y group (P = 0.002), and a significant effect of interaction between HbA1c genetic risk score and postpartum weight reduction on long-term changes in HbA1c was evidenced (P interaction = 0.01). In women with postpartum weight reduction ≥8 kg/y, those with a lower HbA1c genetic risk score had a greater decrease in HbA1c level. CONCLUSIONS: HbA1c genetic risk score interacts with postpartum weight reduction to affect long-term changes in HbA1c levels among women with a history of GDM.