Association of Maternal Vitamin B12 and Folate Levels with Gestational Diabetes Mellitus and Insulin Resistance

Abstract

Background: The incidence of gestational diabetes mellitus (GDM) has increased in recent decades. Established prevention methods for GDM include diet and exercise. Recent interest has focused on the roles of vitamin B12 and folate in the development of GDM. These micronutrients are essential for one-carbon metabolism, which is involved in many metabolic pathways. However, the study results were conflicting and varied by geographic area. Objectives: The aim of this study was to evaluate the relationship between GDM and vitamin B12 levels in our region. Methods: This case-control study enrolled 180 pregnant women at 24 - 28 weeks of gestation. Half of the participants had GDM, and the other half were healthy individuals. All participants attended outpatient pregnancy care clinics at Shiraz University of Medical Sciences from June 2020 to April 2021. Gestational age, age, and body mass index were matched between the two groups. Vitamin B12, folate, insulin, and homocysteine levels were measured in both groups and insulin resistance was calculated. The results were compared between the two groups, and the relationship between vitamin B12 levels and insulin resistance in each group was investigated. Results: Vitamin B12 deficiency was present in 15.6% of the women with GDM. There were no cases of vitamin B12 deficiency in the control group. The GDM group had lower vitamin B12 levels (365.22 ± 136.82 pg/mL vs. 496.08 ± 156.46 pg/mL, P = 0.001). There was a negative correlation between serum vitamin B12 level and insulin resistance index (P = 0.001, r = -0.62). Folate levels were higher in the GDM group (17.93 ± 3.66 ng/mL vs. 14.60 ± 5.32 ng/mL, P = 0.001), but these levels did not significantly relate to insulin resistance or GDM. Conclusions: In our region, there is a significant relationship between low levels of vitamin B12 and both insulin resistance and GDM, which suggests the need for larger studies and attention to the detection and treatment of vitamin B12 deficiency during pregnancy.