Study Determines Association Between Mortality Rates and Sleep Duration in Adults with Type 2 Diabetes

Results from a study published in the Diabetologia determined an association between higher mortality rates and extremes of sleep duration in adults with type 2 diabetes.¹

The study was based on data from the United States and was conducted by a team of Chinese investigators hoping to determine to what extent the effects of sleep duration interacted with diabetes. The team also aimed to examine how sleep duration related to all-cause and cause-specific mortality in individuals with this disease.¹

A total of 273,029 individuals participated in the study; 248,817 individuals without diabetes and 24,212 with type 2 diabetes. The individuals were part of the National Health Interview Survey conducted from 2004 and 2013.¹

In the survey, individuals were asked “on average how long do you sleep each day?” on a 5 to 10 hour per day scale. From this data, the team of investigators employed a Cox proportional hazards regression model, which adjusted for demographics, body mass index (BMI), lifestyle behaviors and clinical variables, to determine the relation between higher death rates and differences in the number of hours slept.¹

Mortality numbers were determined out of 10,000 person-years. For both groups with and without diabetes, the reference number of hours was 7.¹

The investigators used individuals without diabetes who slept 7 hours as the reference comparison group. The model found that absolute mortality rate in adults tended to be higher in those with diabetes and those who demonstrated extremes of sleep duration—extremes being sleeping less than 5 hours per day, or more than 10 hours per day—when compared with the reference group. At less than 5 hours, the mortality rate was 215 per 10,000 person-years; at more than 10 hours, the rate was 364 per 10,000 person-years.¹

A similar but more subdued pattern emerged in the other group, with individuals without diabetes in the 7-hour reference group having a mortality rate of 78 per 10,000 person-years. Those without diabetes who slept for less than 5 hours had a death rate of 122; those who slept more than 10 had a rate of 256.²

The new study found an association between sleep duration, type 2 diabetes, and cause-specific mortality. Cancer mortality was 41% higher in individuals with diabetes who slept less than 5 hours per day, and 59% in those who slept more than 10. Cardiovascular disease (CVD) mortality was statistically higher for 10-hour sleepers, at a 74% increased risk, when compared with 7 hours of sleep. The longest sleep groups further demonstrated an increased risk of death by stroke or Alzheimer disease.²

Previous research, the authors noted, already demonstrated that extreme levels of sleep duration could have significantly negative effects on an individual, and that poor sleep could result in a 40% slower glucose clearance rate for the body. For individuals with diabetes, this could prove fatal, as a slower rate could aggravate the status of insulin resistance, obesity, and high blood pressure.²

The team noted, however, that the data gathered was still based on self-reported information, without use of objective measurements. The study also did not include non-fatal events that may have contributed variables to the risk of death. Additionally, the study lacked data on other factors, such as the number and age of young children, and the kind of employment, medications, and mental illness, that could have contributed to the quality of sleep, and therefore the hours spent sleeping.¹

Nevertheless, the team emphasized the importance of having a sufficient and healthy sleep duration. They recommend that both individuals with and without type 2 diabetes get 6 to 8 hours of sleep per night.²

In reference to their findings regarding higher rates of death in individuals with type 2 diabetes, the team posited the possibility of including sleep interventions in present diabetes treatments. “These patients may require greater medical attention that targets sleep and lifestyle to reduce the risks of adverse health outcomes,” the investigators concluded.¹

References

1. Wang Y, Huang W, O’Neil Adrienne, et al. Association between sleep duration and mortality risk among adults with type 2 diabetes: a prospective cohort study. Diabetologia. July 16, 2020. https://doi.org/10.1007/s00125-020-05214-4
2. Study finds link between too much or too little sleep and increased death rates in patients with or without diabetes. News Release. EurekAlert!. Accessed July 20, 2020. Published July 16, 2020. https://www.eurekalert.org/pub_releases/2020-07/d-sfl071420.php