Associations of Circadian‐Disruptive Behaviours With Plasma Glycemic Parameters and Continuous Glucose Monitoring Measures Among Pregnant Women

ABSTRACT Aims Circadian‐disruptive behaviours (CDBs) may impair glucose regulation via central and peripheral clocks. This study investigated the association between CDB burden and glycemic outcomes during pregnancy. Materials and Methods In this prospective cohort study, 246 pregnant women were recruited at 18–24 weeks' gestation. Four CDBs were assessed using dietary records and questionnaires: eating jetlag, predominant night‐eating, social jetlag, and electronic media use before bedtime. Outcomes included oral‐glucose‐tolerance‐test (OGTT) and insulin parameters (24–28 weeks' gestation) and continuous‐glucose‐monitoring (CGM) metrics (18–24 weeks' gestation). Skewed outcomes were log‐transformed, and associations with the number of CDBs were examined using multivariable regression. Results Compared with women without CDBs, those with two CDBs had higher fasting insulin [geometric mean ratio 1.23 (95% CI 1.02, 1.48)] and updated‐homeostasis‐model‐assessment‐of‐insulin‐resistance (HOMA2‐IR) [1.23 (1.02, 1.47)]. Women with three or four CDBs had significantly higher fasting glucose [1.09 (1.04, 1.15)], 1‐h glucose [1.17 (1.03, 1.33)], glucose area‐under‐the‐curve [1.14 (1.03, 1.26)], and lower updated‐homeostasis‐model‐assessment‐of‐β‐cell‐function (HOMA2‐%B) [0.76 (0.62, 0.93)]. Furthermore, fetal sex modified the associations between CDBs and CGM‐derived glycemic control measures, including mean glucose, glucose management indicator (GMI), and J‐index (all p interaction < 0.1). In stratified analyses, a higher cumulative CDB measure was significantly associated with higher glycemic control measures among women carrying female foetuses. Conclusions Higher CDB burden was associated with less favourable glycemic profiles and lower HOMA2‐%B during pregnancy. These findings support investigating circadian‐aligned lifestyle strategies to improve maternal metabolic health. Trial Registration: ClinicalTrials.gov identifier: NCT03803345.