Effect of zinc supplementation on insulin resistance and lipid profiles in women with gestational diabetes

Objective: The aim of this study is to determine the effects of zinc supplementation on insulin resistance and lipid profiles in gestational diabetes.

Study design: Parallel double-blind (both patients and researchers) randomized controlled clinical trial.

Population and sample size: 58 patients with gestational diabetes mellitus among pregnant women of eligible and referred to Kosar Gynecology Clinic affiliated to Arak University of Medical Sciences, Arak, Iran in the study will be selected.

Inclusion Criteria: Pregnant women aged 18-40 years diagnosed with gestational diabetes mellitus at 24-28 weeks' gestation. Exclusion Criteria: Taking zinc supplements, premature preterm rupture of membrane, placenta abruption, pre-eclampsia, eclampsia, hypo- and hypothyroidism, the use of substitute treatments including hormone or vitamin supplements, complete bed rest (CBR), intra uterine fetal death (IUFD), preterm delivery.

Intervention group: Zinc capsule (Donyayeh Behesht Pharmaceutical Company, Tehran, Iran), 30 mg, once a day for 6 weeks orally. Control group: Placebo capsule (Barij Essence Pharmaceutical Company, Kashan, Iran), once a day for 6 weeks orally. Patients will be assigned to receive either zinc (n=29) or placebo (n=29) for metabolic profiles, and to receive either zinc (n=20) or placebo (n=20) for gene expression.

Outcomes: Insulin and insulin resistance (primary outcomes). Fasting plasma glucose and lipid profiles, pregnancy outcomes (secondary outcome).

Conducted date: August 2014 to April 2016. Publication date: The effect of zinc supplementation on expressed levels of peroxisome proliferator-activated receptor gamma and glucose transporter type 1 genes in newborns of women with gestational diabetes mellitus; Publication date: 22 June 2016. Zinc supplementation and the effects on pregnancy outcomes in gestational diabetes: a randomized, double-blind, placebo-controlled trial; Publication date: 14 October 2015. Zinc supplementation and the effects on metabolic status in gestational diabetes: A randomized, double-blind, placebo-controlled trial; Publication date: 4 July 2015. The number of update: 2. Reason for update: Due to an error, the request for an update in our website has conducted after paper published. However, the revisions were in accordance with either the original approved proposal or with coordination with Vice Chancellor of Research at the University.

Arak University of Medical Sciences

At study baseline after balanced blocked randomisation, participants will be allocated into two treatment groups to take either zinc supplements (n = 29) or placebo (n = 29). Randomization will be done by the use of Stat Trek software. Participants, investigators or the assessors of the outcomes are also unaware of the study groups.

Randomization and allocation will be concealed from the researchers and participants until the final analyses are completed. Another person at the Clinic who is not involved in the trial and not aware of random sequences will allocate the numbered bottles of capsules to participants. Supplements and placebo are in the same packaging at the pharmaceutical company. Only the code is written on the packages. Patients and researcher do not know the type of drug and after analyzing the data, packet codes are decoded.