New study reveals critical links between sleep patterns and diabetes risk, highlighting why monitoring your sleep health could prevent type 2 diabetes progression after gestational diabetes.
Study: Sleep Characteristics and Long-Term Risk of Type 2 Diabetes Among Women With Gestational Diabetes. Image Credit: Pixel-Shot / Shutterstock
In a recent study published in the journal JAMA Network Open, researchers assessed the associations between sleep quality/duration and the risk of type 2 diabetes (T2D) in females with gestational diabetes (GD).
Around one-third of adults in the United States in 2020 regularly slept less than seven hours daily. Mounting evidence suggests that shorter sleep duration and frequent snoring correlate with a higher T2D risk. GD is among the most common complications in pregnancy and affects 2%–30% of pregnancies globally. Females with GD have higher odds of developing T2D later in life.
Females with GD experience insulin resistance and β-cell dysfunction during pregnancy, which may deteriorate over time. As such, they develop T2D much earlier than the general public. While studies have examined several modifiable risk factors, such as physical activity and diet quality, the association between sleep and T2D risk remains unclear in this high-risk population.
About the study
In the present study, researchers examined the associations of daytime sleepiness, sleep duration, and snoring frequency with T2D risk in females with GD. The study population included GD subjects from the Nurses’ Health Study (NHS) II, a prospective cohort study that recruited female nurses. The present study included NHS-II subjects who answered questions related to sleep characteristics in the 2001 questionnaire.
Subjects were excluded if they had T1D, T2D, cardiovascular disease, cancer, multiple-gestation pregnancies, T2D before GD, or missing data. Sleep characteristics were reported once in 2001; participants specified whether they snored and how many hours they slept in 24 hours. Participants who reported having T2D received a supplementary questionnaire about diagnostic tests, symptoms, and hypoglycemic therapy.
Biomarkers of glucose metabolism, such as C-peptide, glycated hemoglobin (HbA1c), and insulin, were assessed. Participants were followed up until the last questionnaire, T2D diagnosis, death, or June 2021. Cox proportional hazard regression models were used to determine the associations between sleep characteristics and T2D risk, adjusted for covariates.
Covariates included familial diabetes history, parity, ethnicity/race, use of oral contraceptives, night shift work, menopausal status, depression, respiratory illnesses, antidepressant use, smoking, physical activity, caffeine consumption, alcohol intake, body mass index (BMI), total energy intake, and use of medicines affecting sleep. Biomarkers were compared across sleep categories using least-squares means.
Findings
The study included 2,891 participants, on average aged 45.3 years. During a mean follow-up of 17.3 years, 563 incident T2D cases occurred. At baseline, regular snorers were more likely to be smokers, use sleep-affecting medications, and have depression, respiratory illnesses, higher BMI, lower diet quality, and reduced physical activity than never or rare snorers.
Further, subjects with less sleep (≤ six hours daily) were more likely to be night shift workers and postmenopausal and have higher BMI and caffeine intake than those with seven to eight hours of sleep per day. Participants with a higher daytime sleepiness frequency were more likely to use sleep-affecting medicines, had higher BMI and caffeine intake, and were less physically active than those who never or rarely experienced daytime sleepiness.
The researchers observed significant associations between both occasional (1–2 nights per week) and regular (≥3 nights per week) snoring and higher T2D risk, with even occasional snoring increasing risk notably. People who slept ≤ six hours daily had a significantly increased T2D risk compared to those sleeping seven to eight hours per day. However, sleeping ≥ nine hours per day was not associated with T2D risk. Subjects who experienced daytime sleepiness for ≥ four days weekly had an increased T2D risk in age-adjusted models, but this association became non-significant after fully adjusting for covariates, including BMI.
Besides, participants who snored regularly and slept less had the highest T2D risk, with a hazard ratio (HR) of 2.06. The biomarker analysis included 527 subjects with sleep data and fasting blood samples. Regular snorers had significantly higher levels of HbA1c than rare snorers. Significant positive associations were observed between snoring frequency and higher levels of HbA1c, C-peptide, and insulin (p=0.01 for all). However, sleep duration and daytime sleepiness were not significantly associated with these biomarkers after adjustment.
Conclusions
In summary, the study found that less sleep and both occasional and frequent snoring were associated with a higher risk of T2D in females with a history of GD. Snoring frequency was also associated with an unfavorable metabolic profile. These results highlight the importance of sleep health in this high-risk population and suggest that strategies to prevent GD-to-T2D progression should incorporate sleep health, with emphasis on monitoring snoring and sleep duration. However, sleep characteristics were only reported once at baseline, possibly underestimating the true associations.