Objective To evaluate the serum sortilin levels in pregnant women with gestational diabetes mellitus (GDM) and to compare the results with normoglycemic healthy pregnant women and observe the relationship between serum sortilin levels and biochemical parameters. Methods This case-control study consisted of 55 pregnancies with GDM and 32 healthy singleton pregnancies matched for maternal and gestational age. The maternal serum levels of sortilin were measured with enzyme-linked immunosorbent assay and compared between groups. Results Sortilin levels were significantly higher in GDM group (5.52 +/- 3.19 ng/mL versus 3.30 +/- 1.47 ng/mL, p < .001). Pairwise comparisons showed that both the diet group and insulin group had significantly higher serum sortilin levels than the control group (p: .022 and p: .002, respectively). Maternal serum sortilin levels were significantly positively correlated with serum insulin levels, homeostasis model assessment of insulin resistance (HOMA-IR) and glycated hemoglobin values (r: 0.277, p: .012, r: 0.306, p: .005, r: 0.267, p: .012, respectively). Conclusions Serum sortilin levels were significantly higher in women with GDM compared to the control group and were positively correlated with insulin, HOMA-IR and glycated hemoglobin levels. The present results point to the role of sortilin in glucose homeostasis and suggest that it may be a novel marker for GDM.