Effect of prenatal zinc supplementation on adipose tissue-derived hormones and neonatal weight, height and head circumference in women with impaired glucose tolerance test: randomized clinical controlled trial

Background: It is well known that normal pregnancy exposes mothers to a diabetogenic state. The important role of adipose tissue in the regulation of insulin resistance has been repeatedly proven. This organ carries out the regulation of insulin resistance by producing adipocytokines involved in the pathogenesis of gestational diabetes mellitus (GDM). The present study aims to evaluate the effects of zinc supplementation on serum leptin, visfatin, tumor necrosis factor-α (TNF-α), adiponectin and zinc-α2-glycoprotein (ZAG) levels in pregnant women with impaired glucose tolerance test (IGTT) results. Methods: In this randomized, placebo-controlled, double-blind clinical trial, 46 pregnant women with impaired glucose tolerance test results were randomly distributed into zinc (n = 23) and placebo (n = 23) groups and received 30 mg zinc supplement per day in the form of zinc gluconate and placebo, respectively, for 8 consecutive weeks. The study was conducted in the Shabestar district of northwestern Iran. Results: Supplementation after adjusting for confounding variables resulted in a significant reduction in plasma leptin (p = 0.035) and TNF-α (p = 0.027) levels in the zinc group compared with the placebo group. Serum visfatin levels were significantly increased, and serum ZAG levels were significantly decreased in both groups. However, the changes in adiponectin concentration were not significant in either group after intervention nor were the anthropometric parameters in fetuses whose mothers received the zinc supplement. Conclusions: It seems that zinc supplementation may be considered as a complementary supplement together with the medical management of patients with IGT or GDM. However, further studies are needed before definite conclusions can be drawn.