Lipid levels in women with gestational diabetes mellitus (GDM) have been extensively studied, whether low-density lipoprotein cholesterol (LDL-C) is a risk factor for GDM development remains unclear. This study aimed to investigate the correlation between serum LDL-C levels and the risk of GDM. A case-control study was conducted. Glycolipid metabolic and oxidative stress indicators were measured in 696 women with GDM and 1048 healthy pregnant women. Serum LDL-C levels were significantly lower in the GDM group than in the control group (P <
0.001). Subgroup analysis indicated that reduced LDL-C levels were associated with an increased risk of GDM after adjusting for differences in maternal age, pre-pregnancy body mass index (BMI), gestational age at sampling, fasting glucose and insulin levels, and homeostatic model assessment of insulin resistance (odds ratio [OR] 1.372, 95% confidence interval [CI] 1.050-1.794, P = 0.021 for medium-LDL-C subgroup
OR 1.672, 95% CI 1.219-2.294, P = 0.001 for low-LDL-C subgroup). The risk of GDM decreased by 17.6% per 1 mmol/L increase in LDL-C level (OR 0.824, 95% CI 0.733-0.926, P = 0.001). Furthermore, apolipoprotein (apo) A1 and high-density lipoprotein cholesterol (HDL-C) levels were lower, whereas pre-pregnancy and delivery BMI, triglyceride (TG)/HDL-C ratios, and second-trimester fasting glucose levels were higher in the low-LDL-C GDM subgroup than those in the high- and/or medium-LDL-C GDM subgroups (P <
0.05). ApoA1 and HDL-C levels were lower but TG/HDL-C ratios were higher in the medium-LDL-C GDM subgroup than those in the high-LDL-C GDM subgroup (P <
0.05). We concluded that reduced LDL-C levels were associated with an elevated risk of GDM in the study population. Low LDL-C levels correlated with increased BMI and unfavorable TG, HDL, and glucose metabolism.