The Impact of Vitamin D Supplementation on Post-Partum Glucose Tolerance and Insulin Resistance in Gestational Diabetes: A Randomized Controlled Trial.
BACKGROUND
Hypovitaminosis D has been associated with the development of gestational diabetes mellitus (GDM) in many observational studies.


OBJECTIVE
We report the first study of the impact of prenatal vitamin D supplementation on postpartum dysglycemia in GDM patients in a randomized clinical trial.


METHODS
Women with GDM at 12 - 32 weeks of gestation were assigned randomly to either the intervention group (in which serum 25-hydroxy vitamin D [25OHD] levels were measured immediately, n = 48) or the control group (in which the serum was stored and assayed at 6 - 12 weeks post-partum, n = 48). Participants with initial serum 25OHD < 30 ng/mL in the intervention group were instructed to take a total of 700,000 IU vitamin D3 during pregnancy. The primary outcomes were fasting plasma glucose (FPG), insulin, 2-h post 75 g glucose load plasma glucose (2-hPLG), homeostasis model assessment of insulin resistance (HOMA-IR), HbA1C, and 25 OHD at 6 - 12 weeks after delivery.


RESULTS
The mean ± SD of serum 25OHD in the intervention group raised dramatically from 14.6 ± 6.3 to 32.4 ± 14.4 ng/mL, whereas no significant change occurred in the control group (from 17.7 ± 6.1 to 19.3 ± 9.6 ng/mL, P < 0.001). Thirteen participants developed dysglycemia in each group. Mean FPG, 2-hPLG, and HOMA-IR were not significantly different between the groups. There was no significant difference between the groups for maternal and neonatal outcomes.


CONCLUSIONS
Although the high vitamin D supplementation dose in the present study (compared to the 400 IU/day dose usually recommended for pregnancy) safely increases the serum 25OHD, in GDM cases, the higher dose does not affect the plasma glucose level or insulin resistance at short term follow-up after delivery.
Zanjan Metabolic Disease Research Center, Zanjan University of Medical Sciences, Zanjan, IR Iran.
Majid
M
Valizadeh
Student Research Committee, School of Medicine, Zanjan University of Medical Sciences, Zanjan, IR Iran.
Zahra
Z
Piri
Division of Obstetrics and Gynecology, Mousavi Hospital, Zanjan University of Medical Sciences, Zanjan, IR Iran.
Farnaz
F
Mohammadian
Zanjan Metabolic Disease Research Center, Zanjan University of Medical Sciences, Zanjan, IR Iran.
Koorosh
K
Kamali
Laboratory of Vali-e-Asr Hospital, Zanjan University of Medical Sciences, Zanjan, IR Iran.
Hamid Reza
HR
Amir Moghadami
Cord blood; Gestational Diabetes, Blood Glucose; Glucose Tolerance Test; Insulin Resistance; Post-partum Period; Vitamin D
Diabet Med. 2012 Jan;29(1):36-42
21977923
Br J Nutr. 2010 Feb;103(4):549-55
19781131
Diabetes Care. 2013 Jan;36 Suppl 1:S11-66
23264422
Br J Nutr. 1998 Apr;79(4):315-27
9624222
Int J Endocrinol. 2010;2010:351385
20011094
Diabetes Care. 2008 Apr;31(4):701-7
18235052
Eur J Intern Med. 2012 Jul;23(5):465-9
22726378
Am J Obstet Gynecol. 2012 Sep;207(3):182.e1-8
22717271
Diabetes Care. 2001 May;24(5):955-6
11347764
Int J Endocrinol Metab. 2015 Apr 20;13(2):e21696
25892996
Diabetes Res Clin Pract. 2005 Sep;69(3):279-86
16098925
Curr Opin Obstet Gynecol. 2013 Dec;25(6):462-7
24136163
Diabet Med. 2012 Jul;29(7):e25-32
22150870
Diabetes Care. 2007 Jul;30 Suppl 2:S225-35
17596477
Aust N Z J Obstet Gynaecol. 2011 Feb;51(1):26-30
21299505
Endokrynol Pol. 2008 Sep-Oct;59(5):393-7
18979449
Curr Opin Obstet Gynecol. 2011 Dec;23(6):422-6
21986726
Diabetes Care. 2011 Jan;34 Suppl 1:S11-61
21193625
Diabetes Care. 2013 Feb;36(2):260-6
23033239
BMJ. 2013 Mar 26;346:f1169
23533188
Diabetes Care. 2010 Aug;33(8):1798-804
20484133
J Bone Miner Res. 2011 Oct;26(10):2341-57
21706518
Diabetes Care. 2002 Oct;25(10):1862-8
12351492
Diabetes Care. 2008 Oct;31(10):2026-31
18628572
J Biomed Biotechnol. 2012;2012:634195
22988423
Diabetologia. 2014 Sep;57(9):1798-806
24962666
Diabetes Care. 2014 Jul;37(7):1837-44
24760259
J Obstet Gynecol Neonatal Nurs. 2012 May-Jun;41(3):328-38
22834880
Diabetes Care. 2010 Jun;33(6):1379-81
20215450
Am J Obstet Gynecol. 2011 Sep;205(3):253.e1-7
22071053
Int J Endocrinol Metab. 2015 Jan 10;13(1):e22604
25745497
Science. 1980 Aug 15;209(4458):823-5
6250216