TITLE:
Evaluating the Use of Vitamin D Supplementation to Improve Glycaemic Outcome in Type 2 Diabetes Mellitus Patients: A Systematic Review of Evidence
AUTHORS:
Mzwandile A. Mabhala, Adetoyosi Babanumi, Anthony Olagunju, Eloho Akata, Asmait Yohannes
KEYWORDS:
Vitamin D, Tyep 2 Diabetes Mellitus, Glyceamic, Public Health
JOURNAL NAME:
Journal of Diabetes Mellitus,
Vol.7 No.4,
September
22,
2017
ABSTRACT: Background: The evidence indicates that vitamin D [25(OH)D] improves glycaemic
outcomes in type 2 Diabetes mellitus patients. The outcome measures used to
determine the accuracy of this hypothesis are: glycosylated hemoglobin (HbA1c),
fasting plasma glucose (FPG) and homeostasis model assessment-insulin resistance
(HOMA-IR). Methods: We performed a systematic review and meta-analysis
which included all previous randomised controlled trial (RCT) studies that
assessed the effects of vitamin D on glucose metabolism. We carried out an
extensive electronic database search of published and unpublished RCTs,
evaluating the association between vitamin D and glycaemic outcomes in type 2
diabetes mellitus patients. We searched Cochrane Library, PubMed, EMBASE,
CINAHL Plus with Full Text, MEDLINE, BioMed Central, Turning Research Into
Practice (TRIP), Health Technology Assessment (HTA), and Latin American and
Caribbean Health Sciences (LILIACS) between the years 2005 and 2016. The full
texts of relevant studies were retrieved and a snowballing technique was used
to discover further studies missed from the initial database search. This was
done by hand-searching for references within the retrieved articles. Results: A total of 17 studies were included in the review. The pooled effect of 15
studies that measured HbA1c showed an insignificant effect of vitamin D on
HbA1c (Mean difference (MD) = -0.06 mmol/l; 95% CI = -0.26 to 0.14; I2 = 76%). A pooled analysis of seven studies
that measured the effect of vitamin D on blood glucose also found no
significant effect of vitamin D on T2DM (MD = -0.03 mmol/l;
95% CI = -0.69 to 0.63; I2 = 76%). Three
studies that analysed the effect of vitamin D on insulin sensitivity also
observed no significant effect (MD = -1.51 mmol/l; 95% CI = -3.61
to 0.60; I2 = 67%). Conclusion: In conclusion, although
vitamin D has been extensively studied in relation to some glycaemic outcomes
and some indications that increased plasma vitamin D concentrations might be
linked to prevention of T2DM, firm universal conclusions about its benefits
cannot be drawn. Further studies with better designed trials and larger sample
sizes are needed to draw firmer conclusions.