Sleep-disordered breathing may be a risk factor for glucose elevations in GDM

Among women with gestational diabetes mellitus (GDM), increased severity of sleep-disordered breathing (SDB) is associated with poor glycaemic control during the night and early morning, a study has found.

Sixty-five women with GDM (mean age, 35 years; 31 percent on insulin) underwent sleep recordings and 72-hour continuous glucose monitoring (CGM). Their mean bedtime was about 10:30 pm, while mean waking time was around 7:00 am. On average, most participants were overweight or mildly obese, and the mean body mass index (BMI) was 33 kg/m².

The mean time difference between the CGM and the sleep study was 6 days. Sixty-six percent of the population had an apnoea-hypopnea index (AHI) >10. The majority of respiratory events were related to arousals rather than oxygen desaturation. The mean REM-AHI was 30 events/hour and was greater than the non-REM-AHI (13 events/hour).

Linear mixed models adjusted for BMI and medications showed that a 10-unit increase in AHI was associated with elevated glucose levels at night (11 pm–3 am: 0.20 mmol/L, 95 percent confidence interval [CI], 0.04–0.40), which persisted into the morning (8 am: 0.26 mmol/L, 95 percent CI, 0.08–0.4).

Moreover, REM-AHI but not non-REM-AHI was linked to increased nocturnal and morning glucose levels. AHI showed no association with either mean daytime or 24-hour glucose levels.

The present data highlight SDB as a potential risk factor for elevations in glucose at night and early in the morning among women with GDM, researchers said. Long-term prospective studies are needed to validate the findings and examine whether such glucose elevations carry a risk of adverse pregnancy and child outcomes.