【Abstract】 Objective To investigate the relationship between level of serum miR149 and insulin resistance in patients with gestational diabetes mellitus (GDM). Methods 63 gestational diabetes mellitus treated in our hospital from January 2017 to August 2018 were selected as observation group. During the same period, 63 healthy pregnant women Underwent maternity examination in our hospital were selected as control group. The levels of glycosylated hemoglobin (HbA1c) were measured by automatic glycosylated hemoglobin analyzer. The fasting blood glucose (FPG) was measured by biochemical analyzer. The fasting insulin (FINS) was measured by immunoassay analyzer, and insulin resistance index (HOMA-IR) = FPG *FINS/225 was calculated. Realtime fluorescence quantitative PCR (qRT-PCR) was used to detect the level of serum miR-149 expression in all subjects. Pearson was used to analyze the correlations between miR-149 and blood sugar, insulin and other indicators. Logistic regression analysis was used to analyze the related factors affecting insulin resistance. Results Compared with the control group, the levels of HOMA-IR, FPG, FINS, HbA1C and miR149 were higher than that in the observation group (P＜0.05). Pearson analysis showed that the level of serum miR149 was positively correlated with FPG, FINS and HOMA-IR (P＜0.05), but not with HbA1C (P＞0.05). The multivariate logistic regression analysis showed that the high level of serum miR-149 was a risk factor for insulin resistance. Conclusion The level of serum miR149 in patients with gestational diabetes mellitus is upregulated, which may be related to insulin resistance in pregnant women with gestational diabetes mellitus.