Serum Cathepsin D Levels in Pregnant Women with Gestational Diabetes Mellitus: A Case-Control Study

This study aimed to evaluate maternal serum cathepsin D (CTSD) levels in pregnancies complicated by gestational diabetes mellitus (GDM) and to investigate the association between CTSD, glycemic parameters, and perinatal outcomes. Additionally, the diagnostic performance of CTSD in predicting GDM was assessed.

In this prospective cross-sectional case-control study, 88 pregnant women at 24-28 weeks of gestation were enrolled, comprising 44 women with GDM and 44 age-, body mass index (BMI-), and gestational age-matched healthy controls. GDM was diagnosed using a 75-g oral glucose tolerance test (OGTT) according to IADPSG criteria. Fasting peripheral venous blood samples were collected to measure serum CTSD levels via enzyme-linked immunosorbent assay (ELISA). Clinical, biochemical, and perinatal data were recorded. Comparisons between groups were performed using Student's t-test or Mann-Whitney U test, and correlations were evaluated using Spearman analysis. Receiver operating characteristic (ROC) curve analysis was conducted to assess the predictive value of CTSD for GDM.

The two groups were comparable in terms of maternal age, BMI, gestational weight gain, parity, and gestational age at sampling. Serum CTSD levels were significantly lower in the GDM group than in controls (10.1 vs. 15.1 ng/mL; p=0.004). ROC analysis revealed a CTSD cut-off value of 10.2 ng/mL, yielding 52.3% sensitivity, 93.2% specificity, and an area under the curve of 0.677. Serum CTSD levels were negatively correlated with 2-hour OGTT glucose and HbA1c (r=- 0.257 and -0.256; p=0.016 for both).

Maternal serum CTSD levels are reduced in pregnancies complicated by GDM and are associated with glycemic control, suggesting that CTSD may serve as a potential biomarker reflecting inflammation-related metabolic alterations during pregnancy. Further prospective studies are warranted to clarify the predictive and clinical utility of CTSD in the management of GDM.