Abstract:To investigate the relationships of angiotensin converting enzyme (ACE ) gene poly-morphisms with gestational diabetes mellitus (GDM) and pregnancy outcome. Methods Polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP) technique was used to analyze insertion (I I) and deletion (D) polymorphism loci in 136 cases of pregnant women with GDM (GDM group), 118 cases of preg-nant women with abnormal glucose tolerance (GIGT group) and 106 pregnant women with normal glucose tolerance(GNGT group). Then the women were followed up, and the correlations between the SNPs of gene and the pregnant outcome were analyzed. Results The frequency of DD genotype and D allele in the GDM group was higher than that in the GNGT group, while the frequency of II genotype was lower than that in the GNGT group ( P< 0.05). The FPG, Fins, ACE and HOMA-IR in the GDM patients with ID or DD genotype were significantly higher than those in the GDM patients with II genotype (P < 0.05). The incidences of premature rupture of membranes, premature birth, neonatal respiratory distress syndrome, neonatal hypoglycemia and neonatal hyperbilirubinemia in the GDM women with ID or DD genotype were significantly higher than those in the GDM women with I I genotype (P < 0.05). DD genotype and the D allele frequency were the risk factors for GDM ( P< 0.05). DD genotype was the risk factor for adverse pregnancy outcome (P < 0.05). Conclusions DD genotype of single nucleotide polymorphism of (I/D) gene is the independent risk factor for GDMand adverse pregnancy outcome.