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Ojo O, Weldon SM, Thompson T, Vargo EJ. The Effect of Vitamin D Supplementation on Glycaemic Control in Women with Gestational Diabetes Mellitus: A Systematic Review and Meta-Analysis of Randomised Controlled Trials. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2019; 16:ijerph16101716. [PMID: 31100793 PMCID: PMC6572053 DOI: 10.3390/ijerph16101716] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/12/2019] [Revised: 05/12/2019] [Accepted: 05/14/2019] [Indexed: 12/25/2022]
Abstract
Vitamin D deficiency is highly prevalent amongst pregnant women and is linked to a range of adverse complications, including gestational diabetes. However, there is no consensus among researchers regarding the impact of vitamin D supplementation in alleviating adverse effects in gestational diabetes. The objective of this systematic review and meta-analysis was to determine whether supplementation of vitamin D given to women with gestational diabetes can promote glycaemic control. EMBASE and PubMed were searched up to November, 2018. The selection criteria included randomised controlled trials of the effect of vitamin D supplementation (1000-4762 IU/day) on pregnant women with gestational diabetes mellitus. Study data and outcome measures (fasting blood glucose, glycated haemoglobin and serum insulin) were extracted from included studies. Random-effects models were used for meta-analyses. Heterogeneity tests, and analysis of the risk of bias were conducted. Most of the studies were graded as having either low risk or moderate risk of bias although two studies had a high risk of bias in the areas of blinding of participants and personnel, and incomplete outcome data. On the other hand, the heterogeneity statistic (I2) ranged from 0-41% in the studies included. Five randomised controlled trials were selected for this review and meta-analysis (involving a total of 173 participants supplemented with vitamin D and 153 participants as control drawn from the studies). Vitamin D supplementation was associated with a decrease in fasting blood glucose by a mean of 0.46 mmol/L (-0.68, -0.25) (p < 0.001), glycated haemoglobin by a mean of 0.37% (-0.65, -0.08) (p < 0.01) and serum insulin concentration by mean of 4.10 µIU/mL (-5.50, -2.71) (p < 0.001) compared to controls. This review shows evidence that vitamin D supplementation has the potential to promote glycaemic control in women with Gestational Diabetes Mellitus (GDM). However, due to the limited number of studies in the meta-analysis, the conclusion should be interpreted with caution. Further studies are needed to fully understand the exact mechanism by which vitamin D influences glucose metabolism.
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Affiliation(s)
- Omorogieva Ojo
- Department of Adult Nursing and Paramedic Science, University of Greenwich, London SE9 2UG, UK.
| | - Sharon M Weldon
- Department of Adult Nursing and Paramedic Science, University of Greenwich, London SE9 2UG, UK.
- Barts Health NHS Trust, The Royal London Hospital, Whitechapel Rd, Whitechapel E1 1BB, UK.
| | - Trevor Thompson
- Department of Psychology, University of Greenwich, London SE10 9LS, UK.
| | - Elisabeth J Vargo
- Department of Adult Nursing and Paramedic Science, University of Greenwich, London SE9 2UG, UK.
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Grant WB, Karras SN, Bischoff-Ferrari HA, Annweiler C, Boucher BJ, Juzeniene A, Garland CF, Holick MF. Do studies reporting 'U'-shaped serum 25-hydroxyvitamin D-health outcome relationships reflect adverse effects? DERMATO-ENDOCRINOLOGY 2016; 8:e1187349. [PMID: 27489574 PMCID: PMC4951179 DOI: 10.1080/19381980.2016.1187349] [Citation(s) in RCA: 72] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 04/28/2016] [Accepted: 04/29/2016] [Indexed: 12/14/2022]
Abstract
Several reports describe U-shaped 25-hydroxyvitamin D [25(OH)D] concentration-health outcomes, including musculo-skeletal disorders such as falls and fractures, several cancers, cardiovascular disease (CVD), cognitive function, all-cause mortality rates, birth outcomes, allergic reactions, frailty, and some other disorders. This paper reviews reports of U-shaped outcome associations with vitamin D status for evidence of underlying pathophysiological processes, or of confounding, finding that some U-shaped associations appear to be biologically meaningful, but that many could well reflect confounding by factors such as lifestyle, or hypovitaminosis D-related disease onset being masked by self-supplementation that was begun too late to correct developing health problems but before baseline vitamin D status assessment. However, the various U-shaped associations for allergic reactions may be due to vitamin D modulation of the phenotype of the immune response, shifting the Th1-Th2 balance toward Th2 formation. For prostate cancer, there seems to be little effect of 25(OH)D concentration on incidence; however, there is an inverse correlation between 25(OH)D concentration and mortality rates. Future observational studies, and randomized controlled trial data analyses, should include adjustment for data collected on prior long-term vitamin D supplementation and solar UVB exposure, as well as other potential confounders.
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Affiliation(s)
- William B Grant
- Sunlight, Nutrition, and Health Research Center San Francisco , CA, USA
| | - Spyridon N Karras
- Unit of Reproductive Endocrinology, First Department of Obstetrics and Gynecology, Medical School, Aristotle University of Thessaloniki , Thessaloniki, Greece
| | - Heike A Bischoff-Ferrari
- Department of Geriatrics, University Hospital Zurich, Switzerland Centre on Aging and Mobility, University of Zurich , Switzerland
| | - Cedric Annweiler
- Department of Neuroscience, Division of Geriatric Medicine, Angers University Hospital, University Memory Clinic of Angers, UPRES EA 4638, University of Angers , France
| | - Barbara J Boucher
- Honorary Professor, Blizard Institute, Barts & The London School of Medicine & Dentistry, Queen Mary University of London , London UK
| | - Asta Juzeniene
- Oslo University Hospital, The Norwegian Radium Hospital, Institute for Cancer Research, Department of Radiation Biology , Montebello, Oslo, Norway
| | - Cedric F Garland
- Department of Family Medicine and Public Health, University of California San Diego , La Jolla, CA USA
| | - Michael F Holick
- Section of Endocrinology, Diabetes and Nutrition, Department of Medicine, Boston University Medical Center , Boston, MA, USA
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