A randomized clinical trial to study the effect of vitamin D supplementation on insulin sensitivity in Gestational Diabetes Mellitus

Gestational diabetes mellitus (GDM) is a substantional and world wide growing
health concern affecting approximately 10% of all pregnancies. GDM has serious
outcomes for both mother and child. Many research is conducted to identify
which factors increase the risk for GDM, finally to estimate and eventually
reduce the risk of GDM. Decreased serum vitamin D has been proposed as one of
these factors being associated with GDM. Recent observational studies
demonstrated conflicted results between vitamin D deficiency and the diagnosis
of GDM. This trial aims to identify the effect of vitamin D supplementation on
insulin sensitivity in women with GDM. In the future this may lead to
structural vitamin D supplementation during pregnancy

The main objective is to study the effect of vitamin D supplementation on
insulin sensitivity in patients with gestational diabetes mellitus.

The trial is a double blind, randomized placebo-controlled trial.

Follow-up: onset of GDM till the end of pregnancy

Group 1: Cholecalciferol 15.000IU once a week
Group 2: Placebol 15.000IU once a week

The vitamin D dosage is in a safety range and any adverse events are not
expected. Recently the institute of medicine recommended a upper limit dose of
4000IE a day in adults not making a difference in pregnancy. A dose of 10.000IE
once a day appears to be safe in pregnancy. A total number of 5 visits are
scheduled which includes physical examination and a blood sample. The visits
will be combined with the regular care for GDM, two extra visits are necessary
for the OGTT. Three extra blood samples are required in contrast to the regular
treatment. The benefits of participation is that vitamin D may improve the
insulin sensitivity which may prevent or reduces antidiabetic therapy. Vitamin
D may lead to improvement of maternal en neonatal outcomes as discussed in the
literature