Longitudinal associations between maternal blood glucose levels in different pregnancies, glycemic control, and offspring myopia

The association between maternal glycemic status and offspring vision remains unclear. This study aimed to examine the longitudinal associations between maternal glucose concentrations during different pregnancies, glycemic control, and myopia in preschool offspring. This cohort study enrolled 4227 mother-child pairs with children aged 3–6 years, and incorporated both a prospective analysis and a nested case-control analysis as its sub-studies. In the prospective cohort, suspected myopia was defined as non-cycloplegic spherical equivalent (SE) ≤ 0.75 D; a stricter SE ≤ 1.00 D cut-off was used for sensitivity analysis. Clinically-diagnosed myopia cases were extracted from electronic medical information in nested case control analysis. The exposures assessed were gestational diabetes mellitus (GDM), glycemic control, and glycemic indexes throughout pregnancy. All multivariable models were adjusted for key covariates including outdoor time, screen time, via modified Poisson regression and generalized linear regression. A total of 559 (13.7%) children exhibited suspected myopia. Maternal GDM and each additional mmol/L fasting plasma glucose (FPG) in the third trimester were associated with myopia (RR = 1.29, 95% CI: 1.09–1.54; RR = 1.18, 95% CI: 1.04–1.34). Offspring of mothers with GDM and poor glycemic control‌ had a higher risk of myopia (RR = 1.34, 95% CI: 1.10–1.63) compared with unexposed offspring. The nested case-control analysis corroborated these results, and all associations remained significant in the sensitivity analysis with the stricter SE ≤ 1.00 D threshold. Maternal GDM, elevated FPG levels in the third trimester, and poorly-controlled glucose were associated with an increased risk of myopia in offspring.