From news-medical.net
In a recent study published in JAMA Network Open, researchers explored how an individual’s sleep duration and dietary habits are associated with their likelihood of developing type 2 diabetes (T2D).
Their results, obtained from a cohort study, indicate that poor sleep and unhealthy dietary patterns are risk factors for T2D and have implications for public health strategies to prevent diabetes.
Background
Researchers consider people who sleep less than seven hours a day to have short sleep duration, and studies suggest that up to one-third of adults could be short sleepers.
Not receiving adequate sleep may increase the risk of multiple adverse health outcomes, including T2D, since sleep restriction may affect insulin resistance and glucose metabolism.
While increasing sleep duration to at least seven hours a day could reduce T2D risk, many factors limit an individual’s ability to get sufficient sleep, primarily economic pressures, work schedules, and childcare responsibilities.
However, healthy dietary habits could counteract the adverse effects of poor sleep on health, including T2D risk.
About the study
In this UK-based study, researchers hypothesized that following healthy dietary habits would be associated with a lower risk of developing T2D among individuals who are short-sleepers.
The cohort study included assessments of dietary habits, daily sleep duration, and incident T2D as the primary outcome of interest.
For the sleep assessment, participants between the ages of 38 and 71 were asked to report how many hours they slept in each 24 hours, including naps.
People who slept seven to eight hours had a ‘normal’ sleep duration, while six hours was considered ‘mild short’ sleep, five hours ‘moderate short’ sleep, and three to four hours ‘extreme short’ sleep.
The dietary habit questionnaire included questions on consuming unprocessed and processed red meat, vegetables, fruit, and fish.
Individuals who consumed fewer than two servings each of processed and unprocessed red meat items and two or more servings of fish in a week were categorized as healthier, as were those who consumed at least four tablespoons of vegetables and two fruit pieces per day.
Each of these five behaviours was equally weighted so that individuals received a score between zero, representing the unhealthiest, and five, the healthiest. Hospital inpatient records were used to ascertain whether an individual developed T2D.
Researchers analysed the data using proportional hazards regression analysis accounting for a dose-response relationship between T2D risk and sleep duration.
Additive and multiplicative interactions between sleep duration and diet scores were also modelled.
Adjusted models also included sex, ethnicity and race, smoking status, alcohol consumption, body mass index, blood pressure, education, physical activity, and antidepressant use. All-cause mortality was included as a possible competing outcome.
Findings
The study included 247,867 individuals who were 60 years old on average. Slightly over half the sample was female, and nearly 94% reported White Europeans as their race or ethnicity.
Slightly over three-fourths of the sample were categorized as normal sleepers; about 20% had mild short sleep, 4% were moderately short sleepers, and less than 1% were extremely short sleepers.
Only 17% scored five points on the healthy diet score, while 29%, 27.5%, 17.6%, and 1.5% received scores of four, three, two, and one, respectively. About 3.2% of the sample (7905 people) received a T2D diagnosis within a median of 12.5 years.
Compared to the reference group of normal sleepers, people who slept five hours each night were 16% more likely to develop T2D, while those who slept three to four hours were 41% more likely. However, normal sleep was not significantly different from mild short sleep.
Compared to those with the least healthy diets, people who scored four or five on the diet score were 25% less likely to develop T2D. Three, two, and one score were not associated with significantly lower risk than the reference group.
Researchers observed no multiplicative or additive interactions between diet score and sleep duration in both unadjusted and adjusted models. Sensitivity analysis that included all-cause mortality did not change the main findings.
Conclusions
The primary finding from this study indicates that habitually short sleepers may be at increased risk of developing T2D even if they maintain a healthy diet.
Inadequate sleep may impair insulin sensitivity at the cellular level, shift skeletal muscle energy metabolism toward non-glucose oxidation, increase activity in the sympathetic nervous system, and modify microbiota communities in the gut.
Since increasing sleep duration may not be feasible for many people, other strategies must be identified to reduce T2D risk. Interventions that can be investigated include following Mediterranean or similarly healthy diets and increasing physical exercise.
Additionally, future research should address other causes of inadequate sleep unrelated to economic and caregiving needs, such as obstructive sleep apnoea.
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