Long sleep duration and suboptimal glycaemic control in gestational diabetes mellitus: a cross-sectional study in...

To investigate the impact of sleep duration on glucose homeostasis in individuals with gestational diabetes mellitus (GDM).

Cross-sectional observational study.

Secondary-level maternity care at two centres in Ningbo, China.

A total of 381 women with GDM were included (median age 30.6 years (IQR 28.2-33.1); median gestational age 26.0 weeks (IQR 25.0-27.0)). All participants underwent 2 weeks of continuous glucose monitoring (CGM), and nocturnal sleep duration was assessed using a structured questionnaire.

CGM-derived summary metrics were analysed using multivariable linear regression, and 24-hour glucose trajectories were evaluated using functional data analysis (FDA).

Long sleep duration (>9 hours/day) was associated with higher mean glucose, time above range, coefficient of variation, the pregnancy-specific glucose risk index and lower time in range (β values were 2.41 mg/dL, 1.84%, 1.04%, 1.88% and -1.85%, respectively; all p<0.05). Each additional hour of sleep increased glucose levels, variability and risk (β: mean glucose 1.29 mg/dL, time above range 0.89%, coefficient of variation 0.45%, pregnancy-specific glucose risk index 0.91%; all p<0.05), while reducing time in range (β=-0.87%; p<0.05). The FDA showed that participants with long sleep (>9 hours/day) had elevated glucose by 2.1-5.8 mg/dL from 10:55 to 00:45, lasting for 13.8 hours.

In GDM, long sleep duration was associated with less favourable glucose patterns, suggesting possible windows of greater vulnerability in glucose regulation. These findings indicate that sleep behaviours may represent an important behavioural characteristic relevant to clinical glucose management in pregnancy and warrant further investigation.