Context: Questionnaire studies linked symptoms of obstructive sleep apnea (OSA) to the risk of gestational diabetes mellitus (GDM). Whether this association is present when OSA is assessed objectively by polysomnography is not known.

Objective: The objective of the study was to assess the relationship between pregnancy, OSA, and GDM.

Design, setting, and participants: We conducted observational case-control studies using polysomnography in 15 nonpregnant, nondiabetic women (NP-NGT), 15 pregnant women with normal glucose tolerance (P-NGT), and 15 pregnant women with GDM (P-GDM). The groups were frequency matched for age and race/ethnicity. Pregnant women were studied during the late second to early third trimester.

Main outcome measures: Comparisons of OSA diagnosis and sleep parameters between NP-NGT and P-NGT to assess the impact of pregnancy and between P-NGT and P-GDM to explore the association between GDM and OSA were measured.

Results: Compared with NP-NGT, P-NGT women had a higher apnea hypopnea index (AHI) (median 2.0 vs 0.5, P = .03) and more disrupted sleep as reflected by a higher wake time after sleep onset (median 66 vs 21 min, P < .01) and a higher microarousal index (median 16.4 vs 10.6, P = .01). Among the pregnant women, P-GDM had markedly lower total sleep time (median 397 vs 464 min, P = .02) and a higher AHI (median 8.2 vs 2.0, P = .05) than P-NGT women. OSA was more prevalent in P-GDM than in P-NGT women (73% vs 27%, P = .01). After adjustment for prepregnancy body mass index, the diagnosis of GDM was associated with a diagnosis of OSA [odds ratio 6.60 (95% confidence interval 1.15-37.96)]. In pregnancy, after adjusting for prepregnancy body mass index, higher microarousal index significantly associated with higher hemoglobin A1c and fasting glucose levels. Higher oxygen desaturation index was associated with higher fasting glucose levels.

Conclusion: Pregnancy is associated with sleep disturbances. Sleep is more disturbed in GDM than in P-NGT women. There is a strong association between GDM and OSA.