Vitamin D supplementation and insulin resistance in gestational diabetes

Abstract

Topic Overview: Gestational diabetes occurs in the second or last trimester of gestation and affects 223 million women worldwide. When untreated, it may present with complications like macrosomia and pre-eclampsia. The role of vitamin D is becoming more diverse and the presence of its receptors on numerous tissues led this dissertation to explore the impact of vitamin D supplementation on insulin resistance in gestational diabetes. The Research Question: Amongst mothers with gestational diabetes, does vitamin D supplementation decrease insulin resistance? PICO Elements: Population: Mothers with gestational diabetes mellitus, Intervention: Vitamin D supplementation, Comparison: no supplementation or placebo, Outcome: insulin resistance. Method: The search was conducted between June and September 2020 using HyDi, EBSCOhost, Scopus and PubMed scientific literature search platforms. Studies searched were in English, published between 2010-2020 and peer-reviewed. They were either systematic reviews, meta-analyses or randomised controlled trials. Studies with no control were excluded along with studies including mothers with other types of diabetes. A distinction was made between studies using vitamin D supplementation to prevent versus to treat gestational diabetes. Three key meta-analyses and six randomised controlled trials were retrieved and appraised using the CASP tool, the Cochrane Risk of Bias 2 tool and the Joanna Briggs Institute critical appraisal checklist. Results and Conclusion: Results were inconclusive, yet evidence seems to favour more the intervention. Gaps in the literature including small sample sizes and short duration could have accounted for these inconsistencies. Further research is necessary to reach definitive conclusions. Implications and recommendations: Research is needed in the Mediterranean region and a standard guideline defining vitamin D deficiency should be established. Pre-pregnancy risk factors like obesity should be addressed to reduce vitamin D deficiency rates in gestation. Also, health management needs to ascertain that adequately trained personnel and sufficient resources are available to test vitamin D levels.