The Efficacy and Safety of a High Dose of Vitamin D in Mothers with Gestational Diabetes Mellitus: A Randomized Controlled Clinical Trial

Background: During pregnancy and lactation outstanding changes occur in mother’s vitamin D metabolism. This study was carried out to evaluate the efficacy of 300,000 IU vitamin D given intramuscularly on body status in new cases of gestational diabetes mellitus (GDM). Methods: This is a randomized clinical trial with the follow-up period of 3 months. Totally 45 participants were randomly divided into intervention group (IG) and control group (CG). The IG received an IM injection of 300,000 IU of vitamin D, whereas CG did not. The glycosylated hemoglobin A1C (HBA1C), serum 25-OH-D, parathyroid hormone (PTH), serum calcium and phosphorus were measured. Results: Forty five patients including 24 with the mean age of 30.7±6.2 years in the IG and 21 with the mean age of 29.5±4.0 years in the CG participated in the study. The median concentration of serum 25(OH)D3 in the IG was to 62.10 nmol/l after the intervention, showing an increase of around 158%, compared to before intervention (24.25 nmol/l) whereas the CG showed a decrease of around 4.5%. Of the patients, 79.2% of IG and 81.9% of CG suffered to some degree from vitamin D deficiency. These figures were 4.2% and 71.4% for the IG and CG, respectively after the intervention. For the IG, the PTH was significantly lower and Ca was significantly higher after the intervention. The serum Phosphorus before and after the intervention in each group or between the two groups was not significant. Conclusions: The single 300,000 IM dose of vitamin D is regarded as an effective and safe to promptly improve vitamin D status in GDM. Trial Registration Number: IRCT138902113840N1