With rates of type 2 diabetes on the rise around the world, including in the United States, it’s more important than ever before to understand the factors that contribute to people developing this condition — especially if some of those factors can be changed. So far, it’s well established that age, family history, physical activity, body weight, diet, and drug and chemical exposure are some of the factors that can play a role in developing type 2 diabetes.
Lifestyle factors — including what and how much you eat, physical activity and stress levels — are an area where interventions to help prevent diabetes may be possible, which makes them a common topic of type 2 diabetes research. Another lifestyle factor that has gained attention in recent years is sleep, which was the focus of a recent study on diabetes risk in women.
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Different sleep patterns, different diabetes risk
Published in the June 2020 issue of the journal Diabetes Care, the study looked at sleep patterns in 60,068 women who took part in a larger study called the Nurses’ Health Study II. None of the participants in the current analysis had diabetes, heart disease or cancer at the beginning of the study period. The average age of participating women was 54.9 at the beginning, and each participants self-reported their sleep habits in surveys over a follow-up period that lasted, on average, 7.8 years.
Based on survey responses about their sleep habits, the researchers grouped participants into one of six different sleep patterns. Four of these patterns were for participants who reported getting roughly the same amount of sleep each night throughout the follow-up period, based on whether they got closest to 5, 6, 7 or 8 hours of sleep. Two other patterns were for participants who reported getting less sleep, or more sleep, each night as time went on during the follow-up period — regardless of how much sleep they got or where they ended up.
During the follow-up period, 1,797 participants were diagnosed with type 2 diabetes. The researchers then compared sleep patterns in the women who developed diabetes, while also accounting for factors known to affect someone’s risk of developing diabetes like age, obesity, and metabolic risk factors (such as high cholesterol or triglyceride levels). They found that there were, in fact, major differences in the risk of developing diabetes based on the six different sleep patterns.
The researchers used the 7-hour sleep pattern as the basis for comparison with all the other patterns. The 8-hour pattern was associated with a slightly lower risk of developing diabetes, at 0.96 times the risk of the 7-hour pattern. Participants with the 6-hour pattern were 1.17 times as likely to develop diabetes, while this risk rose to 1.43 for the 5-hour pattern. Getting more sleep over the follow-up period carried 1.33 times the risk of developing diabetes, while getting less sleep over time had nearly the same risk, 1.32 times that of the 7-hour sleep pattern.
When researchers controlled for further factors in developing diabetes, including body-mass index (BMI, a measure of body weight that takes height into account) and risk factors that changed over the follow-up period (rather than just looking at cholesterol, for example, at the beginning of the study), the differences in diabetes risk based on the different sleep patterns shrank, but a significant risk remained in participants who got less sleep over time — 1.24 times the risk of the 7-hour sleep pattern.
Sleep more, less diabetes?
The way the results changed once researchers took different factors into account shows just how complex the relationship is between sleep, diabetes risk factors, and actually developing diabetes. It’s possible that some people slept less because of health problems that might contribute to diabetes — or that some people developed certain health-related risk factors in part because they didn’t sleep enough. In other words, it’s impossible to know whether sleeping less is the cause or the effect of certain health issues.
But if you feel like you aren’t getting enough sleep — due to time constraints, poor sleep or health problems that make it difficult to sleep — it’s worth talking to your doctor about ways to get more or better sleep. Improving poor sleep habits may or may not affect your risk of developing diabetes, but it’s almost certain to leave you feeling more energetic, less stressed and in a better mood.