Background: Vanadium compounds have been shown to exert insulin-mimetic effects and thereby control glucose homeostasis. However, studies regarding the levels of vanadium and gestational diabetes mellitus (GDM) are limited and have inconsistent outcomes.

Objective: The aim of this study was to investigate the association of plasma vanadium concentrations with gestational diabetes mellitus (GDM).

Design: A hospital-based case-control study was carried out in urban Wuhan, China from August 2012 to April 2015. Pregnant women who screened for GDM at the outpatient clinics of the Department of Endocrinology, Tongji Hospital were invited to participant in the study. The inclusion criteria were as follows: 1) age ≥ 20 and ≤ 43 years; 2) gestational age at GDM screening ≥ 24 weeks; 3) singleton pregnancy. The investigators excluded women who met any of the following items: history of diabetes (including but not limited to GDM), cardiovascular disease, cancer or other systemic diseases; pharmacologic treatment or dietary supplement use that might influence glucose or lipids metabolism; accompanied by other pregnancy complications; incomplete basic information. The diagnosis of GDM can be made if one or more glucose values are above the cut points of 5.1, 10.0 and 8.5 mmol/L at fasting, 1 and 2 h during a 75-gram oral glucose tolerance test (OGTT). Controls were randomly selected and individually matched to cases by age (± 2 years), gestational age (± 2 weeks) and parity. Finally, 252 GDM cases and 252 matched controls were selected in this study. All participants gave written informed consent before enrolling in the study. Fasting blood samples (≥ 8 h overnight fasting) were collected using anticoagulant tubes and centrifuged at 3000 rpm for 5 min. Plasma were separated from blood cells and stored at -80 ℃ for further assay. Plasma vanadium concentrations were measured using inductively coupled plasma mass spectrometry. Conditional logistic regression and restricted cubic spline model were used to evaluate the associations between plasma vanadium and odds of GDM.

Inclusion Criteria:

• Age ≥ 20 and ≤ 43 years;
• Gestational age at GDM screening ≥ 24 weeks;
• Singleton pregnancy;

Exclusion Criteria:

• History of diabetes (including but not limited to GDM), cardiovascular disease, cancer or other systemic diseases;
• History of receiving pharmacological treatment known to affect glucose metabolism;
• Incomplete basic information.

All the participants enrolled were Chinese women. They gave informed written consent to the study and did not take any medication known to affect glucose tolerance or insulin secretion before participation.