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Meta-Analysis
. 2018 Nov 2;10(11):1637.
doi: 10.3390/nu10111637.

The Role of Vitamin D Oral Supplementation in Insulin Resistance in Women with Polycystic Ovary Syndrome: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Karolina Łagowska  1 , Joanna Bajerska  2 , Małgorzata Jamka  3
Affiliations
Meta-Analysis

The Role of Vitamin D Oral Supplementation in Insulin Resistance in Women with Polycystic Ovary Syndrome: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Karolina Łagowska et al. Nutrients. .

Abstract

Objective: To evaluate the effect of vitamin D supplementation (alone or with co-supplementation) on insulin resistance in patients with polycystic ovary syndrome (PCOS).

Methods: We performed a literature search of databases (Medline, Scopus, Web of Knowledge, Cochrane Library) and identified all reports of randomized controlled trials (RCTs) published prior to April 2018. We compared the effects of supplementation with vitamin D alone (dose from 1000 IU/d to 60,000 IU/week) or with co-supplements to the administration of placebos in women diagnosed with PCOS. The systematic review and meta-analysis protocol was registered in the International Prospective Register of Systematic Reviews (Prospero) as number CRD42018090572.

Main results: Eleven of 345 identified studies were included in the analysis; these involved 601women diagnosed with PCOS. Vitamin D as a co-supplement was found to significantly decrease fasting glucose concentrations and the HOMA-IR value. HOMA-IR also declined significantly when vitamin D was supplemented with a dose lower than 4000 IU/d.

Conclusions: Evidence from RCTs suggests that the supplementation of PCOS patients with continuous low doses of vitamin D (<4000 IU/d) or supplementation with vitamin D as a co-supplement may improve insulin sensitivity in terms of the fasting glucose concentration (supplementation with vitamin D in combination with other micronutrients) and HOMA-IR (supplementation with vitamin D in continuous low daily doses or as co-supplement).

Keywords: 25(OH)D; glucose; insulin resistant; polycystic ovary syndrome; vitamin D.

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Conflict of interest statement

The authors declare no conflicts of interest.

Figures

Figure 1
Figure 1
The search process.
Figure 2
Figure 2
Overall effect of vitamin D supplementation on changes in 25(OH)D concentration in PCOS patients. Heterogeneity: Q = 902.5137, T2 = 163.1096, df = 9 (p < 0.0001); I2 = 99.0%.
Figure 3
Figure 3
Overall effect of vitamin D supplementation on changes in glucose concentration in PCOS patients. Heterogeneity: Q = 21.6993, T2 = 12.4443, df = 9 (p = 0.0099); I2 = 58.52%.
Figure 4
Figure 4
The effect of different doses of vitamin D supplementation on glucose concentration in PCOS patients. High dose D = −1.45, p = 0.5183, T2 = 22.30; Low dose = D = −2.94, p = 0.1064; T2 = 2.49, Test for overall effects: Z = 0.4933 (p = 0.6218).
Figure 5
Figure 5
The effect of supplementation manners on glucose concentration in PCOS patients. Daily intake D = −1.06, p = 0.6518, T2 = 11.29; Weekly intake D = −2.65, p = 0.229; T2 = 17.24, Test for overall effects: Z = 0.4933 (p = 0.6218).
Figure 6
Figure 6
The effect of different types of supplementation on glucose concentration in PCOS patients. Vitamin D alone: D = −1.43, p = 0.5106, T2 = 21.86, Co-supplementation: D = −1.43, p = 0.0146, T2 = 0, Test for overall effects: Z = 0.8704 (p = 0.3841).
Figure 7
Figure 7
Overall effect of vitamin D supplementation on changes in insulin concentration in PCOS patients. Heterogeneity: Q = 19.4134; T2 = 4.6214, df = 9 (p = 0.0219); I2 = 53.64%.
Figure 8
Figure 8
Effect of different doses of vitamin D supplementation on insulin concentration in PCOS patients, high dose D = −0.37, p = 0.8232, T2 = 10.28, low dose D = −1.03, p = 0.3374, T2 = 0.84. Test for overall effects: Z = 33.84 (p = 0.7351).
Figure 9
Figure 9
Effect of different supplementation manners on insulin concentration of vitamin D in PCOS patients. Daily in take D = −0.55, p = 0.4842, T2 = 0.44; weekly in take D = −0.48, p = 0.8346, T2 = 19.51; Test for overall effects: Z = 0.0287 (p = 0.9771).
Figure 10
Figure 10
Effect of different types of supplementation on insulin concentration in PCOS patients. Vitamin D alone: D = 0.93, p = 0.5123, T2 = 3.19; co-supplement: D = −0.93, p = 0.5123, T2 = 5.78; Test for overall effects: Z = 1.6394 (p = 0.1011).
Figure 11
Figure 11
Overall effect of vitamin D supplementation on the HOMA-IR index in PCOS patients. Heterogeneity: Q = 86.9395; T2 = 0.2529, df = 12 (p = 0.000); I2 = 86.20%.
Figure 12
Figure 12
Effect of different doses of vitamin D supplementation on HOMA-IR index in PCOS patients. High dose D = 0.18, p = 0.9914, T2 = 0.29; Low dose D = −0.31, p = 0.0016, T2 = 0.00; Test for overall effects: Z = 1.1770 (p = 0.2392).
Figure 13
Figure 13
Effect of different manners of supplementation with vitamin D on HOMA-IR index in PCOS patients. Weekly in take D = −0.03, p = 0.9120, T2 = 0.30; Daily in take D = −0.30, p = 0.0018, T2 = 0.00; Test for overall effects: Z = 1.0570 (p = 0.2905).
Figure 14
Figure 14
Effect of different types of vitamin D supplementation on HOMA-IR index in PCOS patients. Vitamin D alone: D = 0.06, p = 0.7370, T2 = 0.22; Co-supplement: D = −0.61, p = 0.0388, T2 = 0.16; Test for overall effects: Z = 1.9241 (p = 0.0543).
Figure 15
Figure 15
Funnel plot of standard error by standard differences in the means of plasma: (A) fasting glucose concentrations; (B) fasting insulin concentrations; and (C) HOMA-IR index in selected randomized controlled trials.
Figure 15
Figure 15
Funnel plot of standard error by standard differences in the means of plasma: (A) fasting glucose concentrations; (B) fasting insulin concentrations; and (C) HOMA-IR index in selected randomized controlled trials.
See this image and copyright information in PMC

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