Women with gestational diabetes are nearly seven times more likely to have sleep apnea and to sleep an average of one hour less nightly than do expectant mothers without the condition, a small observational study has shown.
“It is common for pregnant women to experience sleep disruptions, but the risk of developing obstructive sleep apnea increases substantially in women who have gestational diabetes,” Dr. Sirimon Reutrakul of Rush University Medical Center in Chicago, said in a statement. “Nearly 75% of the participants in our study who had gestational diabetes also suffered from obstructive sleep apnea.”
Reports in the literature link sleep apnea in pregnancy to complications such as preeclampsia, hypertension, low birth weights, preterm delivery, and other pregnancy-related adverse outcomes.
Use of continuous positive airway pressure (CPAP) early in pregnancy for women with hypertension and chronic snoring was noted by the investigators to be associated with better blood pressure control and pregnancy outcomes. CPAP treatment in nonpregnant type 2 diabetes patients with sleep apnea has been shown occasionally effective in improving glucose control. Because there are currently no data on the effects of sleep apnea treatment in gestational diabetes, whether CPAP treatment might affect glucose metabolism and pregnancy outcomes is unknown.
Dr. Reutrakul and his associates cited previous studies that increased sleep apnea leads to poor glycemic control, as well as reports that sleep apnea is a major risk factor for insulin resistance regardless of body mass index (BMI). With these data in mind, the investigators compared metabolic and sleep apnea measures in 15 pregnant women who did not have gestational diabetes; 15 pregnant women with gestational diabetes; and 15 obese controls (BMI = 31.0 +/– 4.3 kg/m2) who were neither pregnant nor diabetic. The groups were matched for age, race, and in the pregnant groups, and prepregnancy BMI.
All gestating women were expecting singletons and were either in the latter part of their second term, or the early part of their third. The average gestational age was 28.2 +/– 3.7 weeks in the women with gestational diabetes, and 30.9 +/– 2.0 weeks in the pregnant group without.
The women with gestational diabetes had notably higher measures of prepregnancy BMI than did the pregnant women without gestational diabetes. The BMI of the gestational diabetes cohort at the time of the sleep apnea monitoring also tended to be higher. Most of the pregnant women were overweight (BMI 25.0-29.9 kg/m2) or obese (BMI = 30 kg/m2) based on the prepregnancy BMI (93% of those with gestational diabetes; 67% of those without).
The number of apneas and hypopneas per hour of sleep were measured using polysomnography. Sleep apnea was diagnosed in the women if their apnea-hypopnea index (AHI) score was greater than or equal to 5. Dr. Reutrakul and his colleagues wrote that theirs was the first study to use polysomnography to evaluate overall sleep quality, including apnea, in women with gestational diabetes, compared with pregnant women without gestational diabetes, controlling for confounding factors. Wake time after sleep onset equaled the number of minutes participants were awake between sleep onset and end of the session.
There were a number of statistically significant findings:
After they adjusted for prepregnancy BMI, Dr. Reutrakul and his associates found that a diagnosis of gestational diabetes was strongly associated with a diagnosis of sleep apnea (odds ratio, 6.60; 95% confidence interval, 1.15-37.96). The researchers also found that pregnant women with gestational diabetes slept a median average of 1 hour less than the other pregnant women did (397 minutes vs. 464 minutes). The gestational diabetes cohort also had a median AHI approximately four times higher than the pregnant women without gestational diabetes had (8.2 vs. 2.0), and a higher overall rate of sleep apnea than did the nongestational diabetes group (73% vs. 27%). Compared with controls, a higher AHI was found in pregnant women without gestational diabetes (2.0 vs. 0.5), as was more disrupted sleep as reflected by a higher wake time after sleep onset (66 vs. 21 minutes). Their median microarousal index was also higher (16.4 vs. 10.6).
The researchers noted that women with gestational diabetes gained less weight during pregnancy than the pregnant women without gestational diabetes (BMI increased respectively by 2.2 +/– 2.0 vs. 4.6 +/– 1.9 kg/m2), ruling out any “strong association” between gestational weight gain, gestational diabetes, and sleep apnea.
According to the authors, the study also was limited by its cross-sectional design, which does not indicate whether sleep apnea causes gestational diabetes, or vice versa. Regardless, Dr. Reutrakul stated, “Based on these findings, women who have gestational diabetes should be considered for evaluation for obstructive sleep apnea, especially if other risk factors such as hypertension or obesity are present, and women already diagnosed with sleep apnea should be monitored for signs of gestational diabetes during pregnancy.”
A member of the research team reported financial ties with Pfizer and other industry-related research grant support. See study for list of disclosures. This study was supported by the ResMed Foundation; the diabetes research training center at the University of Chicago, a specialized center of research on Women’s Health; and the National Institutes of Health.