There is evidence that sleep quality is tied to blood glucose levels in many different ways — shorter sleep duration may increase the risk for type 2 diabetes, and once you have diabetes, sleep disturbances are linked to a higher risk of death. There is also evidence that treating sleep disorders could improve outcomes related to type 2 diabetes, so much that sleep quality may be considered an essential tool for diabetes management.
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For the latest study, researchers looked at data from 953 healthy adults who took part in a dietary intervention trial called PREDICT. All participants in this trial consumed eight different standardized meals containing the same number of calories over two weeks, both at a clinic and at home. These meals consisted of different proportions of carbohydrate, protein, and fat, and one — for an oral glucose tolerance test (OGTT) — was 100% carbohydrate, as noted in a Healio article on the study. Participants also had certain sleep-related measurements taken — showing sleep duration, efficiency (how restful sleep actually is), and timing — and and wore continuous glucose monitoring (CGM) devices to measure blood glucose changes over time.
Sleep quality linked to after-breakfast glucose levels
The researchers found that sleep variables — the timing, quantity, and quality of sleep — were significantly linked to glucose changes after eating, particularly after breakfast. This was true both within individual participants over time, and also between different participants. The researchers found that sleep duration and timing integrated with meal composition in their effect on blood glucose levels — with poor sleep having a smaller effect on glucose levels after a high-carbohydrate or high-fat breakfast than after an OGTT. Greater sleep efficiency — both within and between participants — was linked to lower glucose levels after eating regardless of the meal composition. A later sleep midpoint (halfway through a person’s sleep) was also linked to higher glucose after eating, both within the same person over time and in comparisons between people.
The researchers noted that none of the study participants were known to have diabetes, so the results of this study may apply more to diabetes prevention than diabetes treatment. Still, “our data suggest that sleep duration, efficiency and midpoint are important determinants of [after-meal glucose] control at a population level,” they wrote. At the same time, “to optimize sleep recommendations it is likely necessary to tailor these to the individual,” they noted, as shown by the different sleep habits both between different study participants and within individuals over time. But sticking to a regular schedule seemed to be best for glucose control, regardless of a person’s exact habits — as shown by the fact that deviating from a regular sleep pattern was linked to worse glucose control after eating. “These findings underscore sleep as a modifiable, non-pharmacological therapeutic target for the optimal regulation of human metabolic health,” the researchers emphasized.