Impact of Extreme Sleep Durations on Mortality Greater in Diabetics

Chuanhua Yu, MD

Results of a recent analysis including nearly 275k patients is breaking down the apparent risks associated with extreme sleep schedules among adults with type 2 diabetes.

An assessment of patients in the US National Health Interview Survey (NHIS), results indicate too much or too little sleep in patients with type 2 diabetes was linked to increased death rates—with this effect being notably larger than that among nondiabetic patients.

“Extremes of sleep duration were associated with significant increases in all-cause and disease-specific mortality risk among people with type 2 diabetes. The risk was greatest for those who reported the longest mean sleep duration,” wrote study investigators.

Despite previous studies describing the well-established link between extreme sleep durations, whether long or short, and increased risk of mortality, little reliable data was available examining how presence of diabetes could impact this risk. To investigate how this might impact mortality risk, investigators from China designed a study using data from the NHIS.

Examining patients included in the survey from 2004-2013, investigators identified 273,029 adults for inclusion in their study. Of these 273,029, 248,817 did not have diabetes while 24,212 with type 2 diabetes. All patients included in the study had mortality data through the end of 2015.

The primary outcome measure of the study was all-cause mortality. For the purpose of analysis, investigators hoped to further stratify deaths by cause-specific mortality including cardiovascular disease, cancer, chronic lower respiratory disease, Alzheimer’s disease, diabetes mellitus, influenza and pneumonia, and kidney disease.

As part of NHIS, subjects were asked how many hours of sleep they got in a typical 24-hour period. Based on these results, subjects were put into 6 specific groups. These groups were defined as 5 or fewer, 6, 7, 8, 9, and 10 or more hours per day. Investigators defined extreme sleep duration as 5 or fewer hours or more than 10 hours per day.

Investigators used Cox proportional hazards regression model to evaluate relationships between sleep duration and mortality risk. Of note, analyses were adjusted for demographics, education level, income, BMI, lifestyle behaviors and other clinical variables.

Upon analysis, a total of 17,060 deaths occurred among nondiabetic patients during the follow-up period, which lasted a mean of 6.7 years. Among diabetics, 4593 deaths occurred during the follow-up period, which lasted a mean of 5.96 years. Absolute mortality rate was greatest in adults with diabetes and extreme durations of sleep, with rates of 363.5 per 10,000 person-years among those getting 10 or more hours of sleep and 215.0 per 10,000 person-years among those getting 5 or fewer hours of sleep.

Compared to those in the referent group, which was comprised of patients reporting 7 hours of sleep per day, both shorter and longer sleep durations were associated with increased risk of all-cause mortality. Specifically, less than 5 hours per day increased risk 24% (HR, 1.24l 95% CI, 1.09-1.40), 6 hours per day increased risk by 13% (HR, 1.13; 95% CI, 1.01-1.28), 8 hours per day increased risk 17% (HR, 1.17; 95% CI, 1.06-1.30), and 10 or more hours per day increased risk 83% (HR, 1.83; 95% CI, 1.61-2.08).

Additionally, similar associations were observed for mortality risk from cardiovascular disease, cancer, kidney disease, Alzheimer’s disease, and chronic lower respiratory diseases. Furthermore, short sleep durations were associated with higher risks of all-cause and cardiovascular mortality among individuals treated with both insulin and oral glucose-lowering medications.

This study, “Association between sleep duration and mortality risk among adults with type 2 diabetes: a prospective cohort study,” was published in Diabetologia.