The aim of the current single-blind, placebo controlled randomized clinical trial is to assess the effects of zinc supplementation on insulin resistance and selected metabolic and inflammatory markers in women with impaired glucose tolerance. Total of 46 volunteer pregnant women with impaired oral glucose challenge test, between 24th to 28th weeks of gestation, will be recruited in the study. Those with history of diabetes mellitus, any active infection, chronic metabolic diseases, drug therapy, severe anemia, smoking, alcoholics and recent history of zinc supplements consumption will be excluded. All the participants will be divided into experimental and control groups using permuted blocks random sampling method and will receive 30 mg Zinc gluconate and starch for eight consecutive weeks, respectively. The blood will be drawn via venus puncture and sera will be subjected for analysis of serum glucose and insulin using an auto-analyzer. Also, tumor necrotizing factor α, Leptin, adiponectin, visfatin and Zinc-α2-glycoprotein will be assessed using Enzyme Linked Immunosorbant Assay. Finally, serum zinc levels will be determined by application of graphite furnace atomic absorption spectrophotometry. The data will be entered in SPSS and analyzed by appropriate pairwise comparisons statistical methods to see if there will be any effect of the intervention on the serum levels of the selected biomarkers.