Associations Between Serum Vitamin A Levels in Early Pregnancy and the Risk of Gestational Diabetes Mellitus

Background: The relationship between vitamin A levels and gestational diabetes mellitus (GDM) is not well understood, and prospective studies are lacking. Methods: This was a prospective, longitudinal study. A total of 391 women in early pregnancy were recruited between October and December 2018 at Shunyi District Maternal and Child Health Hospital (Beijing, China). Serum vitamin A concentration was measured at enrollment. GDM was diagnosed on the basis of a 75 g oral glucose-tolerance test at 24-28 weeks of follow-up. Logistic regression was used for the analysis. Results: None of the subjects in the cohort had vitamin A deficiency or excess. At the follow-up, 76 participants had developed GDM. Participants who developed GDM were older and had higher body mass index, fasting insulin, HbA1c, fasting glucose, homeostasis model assessment for insulin resistance, triglyceride, low-density lipoprotein cholesterol, and high-sensitivity CRP levels, as well as higher serum vitamin A levels at baseline. On logistic multivariate analysis, higher vitamin A was positively associated with higher risk of GDM. The adjusted OR was 2.85 (95% CI 1.04-7.80, P=0.042) for Q4 versus Q1 and 1.59 (95% CI 1.11-2.28, P=0.011) for every 1 SD increase in serum vitamin A levels. In participants within the vitamin A reference range (0.33-0.78 mg/L), the positive association also maintained significance. Conclusion: Higher serum vitamin A levels were associated with higher GDM risks, even within the reference range. The results and possible mechanisms need to be further verified and clarified.