Vitamin D status in women with gestational diabetes mellitus

Irish Endocrine Society, Annual Conference, 27 November 2020

A study by a team from South Tipperary General Hospital, Clonmel, which assessed vitamin D status in women with gestational diabetes mellitus (GDM) was presented as a poster presentation at the 2020 IES Annual Conference.

Vitamin D has a modulatory role in insulin secretion and action and is potentially relevant for development of GDM. Observational studies have shown associations between low vitamin D levels and GDM.

A total of 74 women diagnosed with GDM were included in this study. Serum 25(OH)D levels were assessed at diagnosis (median week 25 gestation) and labelled as sufficient (>50nmol/L) or insufficient (<50nmol/L).
The researchers subdivided these groups into those checked in winter (October-March) or summer (April-September).

In total 40 patients (57 per cent) had sufficient levels of vitamin D; 29 (72.5 per cent) of these had levels checked in summer. The remaining 34 (43 per cent) patients had insufficient levels of vitamin D; 14 (41 per cent) of these were assessed in summer.

In total, of those assessed in summer 33 per cent were insufficient, and of those assessed in winter 65 per cent were insufficient in vitamin D. A recent Cochrane review has suggested that supplementation with vitamin D during pregnancy may reduce the risk of GDM and its related complications such as preeclampsia.

Only 57 per cent of women with GDM in this Irish cohort had sufficient vitamin D and the majority (72.5 per cent) of those were checked in summer.

Despite recommendations for vitamin D supplementation in all pregnant women, the study indicates high levels of insufficiency in women with GDM, in whom it may be a causative factor and may also increase risk of complications.