Aim: The purpose of the present study was to investigate changes in insulin sensitivity using homeostasis model assessment (HOMA) and the quantitative insulin sensitivity check index (QUICKI) in normal-weight and overweight women with normal glucose tolerance (NGT) and gestational diabetes mellitus (GDM) during pregnancy.

Methods: Ninety-two pregnant women in the first trimester, 202 in the second trimester and 154 in the third trimester were enrolled in this study. Fasting plasma glucose and insulin concentrations were measured in all women in the first, second and third trimesters. HOMA indices (insulin resistance, HOMA-IR and beta-cell function, HOMA-beta) and QUICKI were calculated from fasting glucose and insulin concentrations.

Results: HOMA-IR values in overweight women with NGT and in women with GDM were significantly (p < 0.01) higher than those in normal-weight women with NGT. HOMA-IR in women with GDM increased significantly (p < 0.05) during pregnancy, but HOMA-IR values in normal-weight and overweight women with NGT did not change significantly with advance of gestation. QUICKI values in overweight women with NGT and in women with GDM were also significantly (p < 0.01) lower than those in normal-weight women with NGT, and QUICKI in women with GDM decreased significantly (p < 0.05) during pregnancy. HOMA-beta in normal-weight women with NGT increased significantly (p < 0.01) during pregnancy.

Conclusion: We showed that insulin sensitivities determined by using HOMA-IR and QUICKI in overweight women with NGT and women with GDM were lower than those in normal-weight women with NGT, and that insulin sensitivity in women with GDM declined with advance of gestation.