Serum 25-hydroxyvitamin D concentrations are lower in women with Gestational Diabetes Mellitus

NL Newlands1 H Shaikh2 N Sultan1 CKH Yu3 TG Teoh3 S Robinson2

1Imperial College School of Medicine, 2Department of Metabolic Medicine Imperial College AHSC, 3Department of Obstetrics and Gynaecology Imperial College AHSC


Background: Serum 25-hydroxyvitamin D (25-OHD) concentrations may relate to risk of gestational diabetes mellitus (GDM) and hypertension in pregnancy. 

Objective and Aim: To investigate 25-OHD concentrations and blood pressure in women with GDM and ethnic matched controls. 

Methods: A prospective cohort study where 97 women with GDM were compared to 145 ethnically matched glucose-tolerant controls. Four ethnic groups were studied: African and Afro-Caribbean (AAC) n=66, Arab-Mediterranean (AM) n=60, South Asian (SA) n=53 and Caucasian (C) n=63.  Mean body mass index (kgm2) was higher in GDM groups: AAC: 29 vs.26 (**), AM: 29 vs.28 (NS), SA: 27 vs.24 (**) and C: 24 vs.26 (NS).

Results: Median 25-OHD levels in the GDM group were 21nmol/L (IQR 14-43) compared to 25nmol/L (IQR 20-37) in the glucose-tolerant control group (NS).  However, when compared within ethnic groups, AAC and AM women with GDM had a significantly lower 25-OHD concentration than controls (AAC: 14nmol/L (IQR 14-28) vs. 23nmol/L (IQR 20-27); p=0.007. AM: 15nmol/L (IQR 14-35) vs. 21nmol/L (IQR 18-31); p=0.047).  Mean Arterial Blood Pressure (MABP) was significantly greater in AAC, AM and SA GDM groups compared to controls (AAC: 92mmHg vs. 87mmHg; p=0.035. AM: 92mmHg vs. 84mmHg; p=0.005.  SA: 89mmHg vs. 83mmHg; p=0.038).  There was no association between 25-OHD and blood pressure or blood pressure change through pregnancy.  

Conclusions: 25-OHD is associated with a diagnosis of GDM in AAC and AM women, but it is not associated with MABP in any of the four ethnic groups.  Further work is needed to understand the mechanisms involved.