The Link Between Lack of Sleep and Mortality in Diabetics

A new study published in the journal Diabetologia found that there are higher mortality rates among people with type 2 diabetes who sleep either too much or too little.

While previous studies have shown that extreme sleep duration (too much or too little) is linked to increased mortality rates in the general population, this study examined how the presence of diabetes influenced the link between short or long sleep durations and the presence of diabetes.

Researchers used data from 273,029 adults, including 248,817 without diabetes and 24,212 with type 2 diabetes, who participated in the U.S. National Health Survey from 2004-2013, and linked their data to mortality data up to the end of 2015. Sleep duration was measured using self-reporting, where participants were asked, "On average, how long do you sleep each day?" (5 hours or less, 6, 7, 8, 9, and 10 or more hours a day). The relationship between sleep duration and mortality was investigated using computerized models adjusted for demographics, body mass index, lifestyle behaviors, and clinical variables..

As expected, regardless of the amount of sleep compared, mortality rates were higher among people with type 2 diabetes than those without diabetes. The mortality rate among people with type 2 diabetes with the ideal level of 7 hours of sleep was 138 per 10,000 person-years, compared to 215 with less than 5 hours of sleep and 364 for people with 10 or more hours of sleep.

After adjusting the data, researchers examined a group of people without diabetes who slept 7 hours a night as the reference or comparison group. Compared to this group, people with type 2 diabetes who slept 7 hours had a 42% increased risk of death. Those with type 2 diabetes and 10 or more hours of sleep had a 2.2 times higher risk, while people with type 2 diabetes who slept 5 hours or less had a 63% increased risk of death.

The study also found that the shortest and longest sleep durations were associated with a greater risk of mortality from all causes compared to those who slept 7 hours a day among people with type 2 diabetes diagnosed before age 45, compared to those diagnosed after age 45. Also, the impact of extreme sleep duration on mortality was generally more pronounced among those who had diabetes for more than ten years compared to less than ten years..

Researchers point to previous studies showing that insufficient sleep causes a 40% slower glucose clearance rate in the body and triggers the sympathetic (involuntary) part of the nervous system, which in turn can cause insulin resistance. "Obesity or high blood pressure can increase complications and affect control and management of blood sugar levels, which drive the excess risk of mortality," they say..

Sleep is a complex phenomenon, and extreme sleep duration may reflect worse health status and reduced functioning. For example, the finding that people with type 2 diabetes who sleep more are at increased risk of mortality might be related to the possibility that these individuals experience more complications related to diabetes requiring more rest or long-term recovery in bed. Another possible explanation for these findings is that longer sleep duration is tied to chronic inflammatory responses that increase mortality risk. People with type 2 diabetes, like the general population, are advised to sleep 6 to 8 hours at night to reduce mortality risk. For diabetics, it is advisable to maintain balanced blood sugar levels using a continuous glucose monitor, engage in 150 minutes of weekly physical activity, and maintain a balanced diet.

Prof. Julio Weinstein is the director of the diabetes unit at Wolfson Hospital and a senior diabetes physician at the DMC Diabetes Care Center.