The electronic databases including PubMed, Scopus and Web of Science were searched for the original articles that evaluated the correlation between glucose metabolism tests including fasting blood glucose (FBG), fasting insulin (FI), homeostatic model assessment for insulin resistance (HOMA-IR), the rate of individuals with HOMA-IR  > 4.5, insulin resistance, fasting glucose/fasting insulin (FG/FI) and FG/FI  > 4.5.and recurrent pregnancy loss with a combination of proper keywords. The gene discussed is INS; the disease is Insulin resistance.