Zinc-Associated Variant in SLC30A8 Gene Interacts With Gestational Weight Gain on Postpartum Glycemic Changes: A Longitudinal Study in Women With Prior Gestational Diabetes Mellitus

Zinc transporter 8 genetic variant SLC30A8 has been associated with postpartum risk of type 2 diabetes among women with gestational diabetes mellitus (GDM). Gestational weight gain is one of the strongest risk factors for postpartum hyperglycemia. We assessed the interaction between type 2 diabetes-associated SLC30A8 rs13266634 and gestational weight gain on 1-5 years of postpartum glycemic changes in 1,071 women with prior GDM in a longitudinal study. Compared with gestation of 26-30 weeks, postpartum levels of fasting glucose, oral glucose tolerance test 2-h glucose, and hemoglobin A1c (HbA1c) increased across rs13266634 TT, CT, and CC genotypes in women with excessive gestational weight gain, whereas opposite genetic associations were found in women with inadequate or adequate gestational weight gain. Postpartum changes in fasting glucose per additional copy of the C allele were -0.18, -0.04, and 0.12 mmol/L in women with inadequate, adequate, and excessive gestational weight gain, respectively (P for interaction = 0.002). We also found similar interactions for changes in 2-h glucose and HbA1c (P for interaction = 0.003 and 0.005, respectively). Our data indicate that gestational weight gain may modify SLC30A8 variant on long-term glycemic changes, highlighting the importance of gestational weight control in the prevention of postpartum hyperglycemia in women with GDM.