The study’s authors noted that life expectancy has been increasing more slowly or even declining in many countries in recent years, and that an increase in many diseases — including diabetes — is linked to this worsening of life expectancy. Since diabetes is also associated with sleep disturbances, the researchers wanted to explore whether there is a connection between sleep disturbances in diabetes and a higher risk of death. They used data from a large British study called the UK Biobank, following 487,728 participants for an average of 8.9 years.
Sleep disturbances in study participants were assessed through one survey question, asking if they have trouble falling asleep or wake up in the middle of the night. The researchers grouped the responses “never/rarely” and “sometimes” into a single category, and compared these people with those who answered “usually” to the question about sleep disturbances. The researchers then compared the risk of death in these two groups, and also looked at the death risk in the subset of people in each group with diabetes.
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Out of all study participants, 5.0% had diabetes. based on self-reporting of their diagnosis or insulin use. Not surprisingly, people with diabetes were overrepresented among participants with sleep disturbances, with 6.3% of those who answered “usually” to the sleep question having diabetes, compared with 4.6% of those who answered “sometimes” and 4.4% of those who answered “never/rarely.” Diabetes wasn’t the only factor that made people more prone to sleep disturbances, though — other factors included older age, a higher body-mass index (BMI, a measure of body weight that takes height into account), currently smoking, having depression, and being a woman or white.
Frequent sleep disturbances linked to the risk of death
During the follow-up period, there were 19,177 deaths from all causes and 3,874 deaths from cardiovascular disease. Frequent sleep disturbances were significantly linked to the risk of death after adjusting for age and sex — those who answered “usually” to the sleep question were 31% more likely to die from any cause, and 33% more likely to die of cardiovascular disease. After adjusting for other factors, people who gave this answer were still 13% more likely to die from any cause, but only 2% more likely to die of cardiovascular disease, which wasn’t a significant difference.
After adjusting for all known other factors, people with diabetes but no frequent sleep disturbances were 67% more likely to die than those without diabetes or frequent sleep disturbances, and those with both diabetes and frequent sleep disturbances were 87% more likely to die than those without either condition — nearly twice as likely. These numbers mean that having frequent sleep disturbances along with diabetes was linked to a 12% higher risk of death than having diabetes alone. For death from cardiovascular disease, the risk of death was 104% higher for people with diabetes but no frequent sleep disturbances and 111% higher for those with both diabetes and frequent sleep disturbances. This represents only a 3% higher risk for those with both diabetes and frequent sleep disturbances, compared with just diabetes — not a significant difference.
“To our knowledge, this is the first study to examine the effect of the combination of insomnia and diabetes on mortality risk,” the researchers wrote. “Frequent sleep disturbances may be an important health indicator for clinicians to consider, particularly for diabetes patients,” they concluded, adding that “a single question was sufficient to detect mortality risk, and clinicians could use a similar brief question to identify patients who may need additional therapy or support.”
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