Elderly who snore or have sleep apnea are almost twice as likely as sound sleepers to develop type 2 diabetes, revealed a new study.
Findings from some 6,000 U.S. adults who were followed for up to 10 years suggest that doctors may want to monitor blood sugar in older patients with sleep-disordered breathing, researchers say.
"Recent evidence suggests that diabetes patients have a higher prevalence of sleep disturbances than the general population," said Linn Beate Strand, lead author.
"However, less is known about whether symptoms of sleep-disordered breathing increase the risk of developing type 2 diabetes later, especially in older adults," said Strand, of the Beth Israel Deaconess Medical Center in Boston.
Sleep apnea involves frequent episodes during sleep when the airway closes and people stop breathing entirely. Often breathing resumes abruptly with a loud snort or choking sound, according to the National Heart, Lung and Blood Institute.
These repeated breathing interruptions, which can occur up to 30 times per hour, have been linked to daytime sleepiness and increased risk of high blood pressure, heart attack, stroke, heart failure, irregular heartbeat, diabetes and death. Most previous studies on sleep disorders and diabetes have focused on young or middle-aged adults, the researchers point out in the Journal Diabetes Care
. But, Strand told sleep apnea and snoring become more common with age.
Strand and colleagues analyzed data from 5,888 adults who were recruited from across the U.S. between 1989 and 1993, when they were 65 or older. None had type-2 diabetes when they enrolled.
Every six months through 1999, the researchers asked the seniors whether anyone had observed them having episodes of sleep apnea, whether a spouse or roommate had complained about their loud snoring and whether they were usually sleepy in the daytime. In addition, the researchers asked about insomnia symptoms such as difficulty falling asleep, frequent awakening at night or waking up too early and being unable to go back to sleep.
Participants' level of insulin, a hormone that regulates blood sugar, was measured early in the study, and their fasting blood sugar levels were measured multiple times over the years. Researchers also took note of who developed type 2 diabetes during the course of the study.
Older adults who reported snoring, sleep apnea or daytime sleepiness tended to have higher fasting blood sugar levels than normal sleepers. They also had insulin resistance, meaning they produced higher than normal amounts of insulin but their bodies were less able to use it to control their blood sugar levels.
People with sleep apnea were nearly twice as likely as normal sleepers to develop diabetes, and snorers were 27 percent more likely. Those with daytime sleepiness were also about 50 percent more likely than those without that symptom to develop diabetes.
"Monitoring blood sugar levels in older adults with sleep disturbances may help identify individuals potentially at risk to allow earlier interventions" before they develop full-blown diabetes, Strand said.
The more disturbed-breathing symptoms people had during sleep, the greater their diabetes risk. Insomnia symptoms, however, were not consistently linked to the risk of diabetes.
"The findings suggest that improving sleep quality in older adults may reduce their risk of developing diabetes or may reduce the severity of diabetes in those who are already affected," Eve Van Cauter, who was not involved in the study.
Van Cauter, a sleep and metabolism researcher at the University of Chicago, noted that although sleep disturbances can cause problems for nearly all aspects of health, they're often ignored when treating diabetes.
"Getting good sleep is as important as nutrition and exercise to remain healthy during the aging process. People must insist that their doctors include sleep hygiene and sleep health in their evaluation and recommendations," Van Cauter noted.