Getting enough sleep could help prevent type 2 diabetes
Men who lose sleep during the work week may be able to lower their risk of developing Type 2 diabetes by getting more hours of sleep, according to Los Angeles Biomedical Research Institute (LA BioMed) research findings presented today at The Endocrine Society’s 95th Annual Meeting in San Francisco.
The study by Peter Liu, MD, PhD, an LA BioMed lead researcher, found that insulin sensitivity, the body’s ability to clear glucose (blood sugar) from the bloodstream, significantly improved after three nights of “catch-up sleep” on the weekend in men with long-term, weekday sleep restrictions.
“We all know we need to get adequate sleep, but that is often impossible because of work demands and busy lifestyles,” said Dr. Liu. “Our study found extending the hours of sleep can improve the body’s use of insulin, thereby reducing the risk of Type 2 diabetes in adult men. Reducing the incidence of this chronic illness is critical for a nation where diabetes affects nearly 26 million people and costs an estimated $174 billion annually.”
Insulin is a hormone that regulates a person’s blood sugar level. The body of a patient with Type 2 diabetes cannot effectively use the insulin it produces, or it becomes “resistant” to insulin. Retaining the body’s sensitivity to insulin reduces the risk of developing Type 2 diabetes, a chronic illness that is the seventh leading cause of death in the U.S.
Other research had demonstrated the harmful effects of experimental sleep restriction on insulin sensitivity in healthy, normal sleepers. The new study provides information about people who lose sleep during the week – often because of jobs and busy lifestyles – but “catch up” on their sleep on the weekends.
“The good news is that by extending the hours they sleep, adult men – who over a long period of time do not get enough sleep during the working week – can still improve their insulin sensitivity,” Liu said.
Liu and researchers from the University of Sydney in Australia studied 19 non-diabetic men, with an average age of 28.6 years, who for six months or longer (average, 5.1 years) self-reported inadequate sleep during the workweek. On average, the men received only 6.2 hours of sleep each work night. But they regularly caught up on their sleep on the weekends, sleeping an extra 37.4 percent, or 2.3 hours, per night, the authors reported. Their reported sleep times were verified by actigraphy, in which each man wore a small device on his wrist that monitored sleep-wake cycles.
The men spent three nights in a sleep lab on each of two separate weekends. The researchers randomly assigned the men to two of three sleep conditions: (1) 10 hours of sleep, (2) six hours of sleep or (3) 10 hours in bed, in which noises during deep sleep aroused them into shallow sleep without waking them. The six hours of sleep tested persistent sleep restriction.
Given the serious consequences emanating from insulin resistance and Type-2 diabetes, preventing this disease is certainly our best weapon in reducing the damage caused by a surplus of blood sugar. Luckily for us, the preventive potential is extraordinary: Adopting a healthy lifestyle can prevent up to 90 percent of Type-2 diabetes cases! To see how we can reduce the risk of diabetes, let us review some lifestyle factors.
1. Maintain a healthy body weight
Given that excess weight and obesity are instrumental in the development of Type-2 diabetes, maintaining a normal body weight is an essential aspect of any preventive approach. The most spectacular illustration of how weight loss can influence the risk of diabetes is undoubtedly the effect of bariatric surgery (reducing stomach size) on morbidly obese people. Radically reducing the size of the stomach rapidly decreases obesity and almost completely eliminates Type-2 diabetes!
However, it is neither necessary nor desirable to undergo this type of surgery to reap the benefits of weight loss: Losing just 5 kg, even over several years, can reduce the risk of diabetes by 50%! At a time when overweight has become the norm rather than the exception, Type-2 diabetes undoubtedly illustrates the dangers of excess weight and the need to be as slim as possible in order to prevent this disease.
2. Reduce intake of high-sugar foods
You can also significantly reduce the risk of diabetes by paying particular attention to the amount and especially the type of carbohydrates: that is, the sugar in your diet. There are three main types of carbohydrates.
• The first is simple sugars – like those in fruits, dairy products, maple syrup, or honey – and sugars added to various products sold in grocery stores. Added sugar is quite significant: In 2001, it represented more than 10% of the calories consumed by Canadians, or the equivalent of 60 g (12 teaspoons) of sugar a day! This sugar surplus is sometimes difficult to identify as the industry uses many sources of sugar in its preparation of food products. But make no mistake. When a product label uses terms like sucrose, dextrose, fructose-enriched corn syrup, glucose-fructose, malt syrup, etc., it can mean only one thing: sugar has been added! The closer these items are to the top of the ingredient list, the more of them the product contains.
On the fourth morning, the research staff drew the men’s blood to measure their blood sugar and insulin levels to calculate insulin sensitivity. Each individual had the same food intake during the study visits, so that diet would not influence the results, Liu said.
When the men slept 10 hours a night on each of three nights of catch-up sleep, their insulin sensitivity was much better than when they had persistent sleep restriction, the scientists found. Their insulin resistance test score also improved (decreased) with sleep extension.
• The second main form of sugar is starches. These are created by combining a number of sugar molecules. Starch is found in cereals, potatoes, and certain vegetables and legumes. Generally, the sugar present in foods in starch form is digested more slowly than simple sugars. Conversely, all starches are not digested at the same rate: For example, potato starch has a structure that breaks down into sugar very quickly while legume starches are much more resistant.
• The third main form is dietary plant fibres, found only in plant products such as vegetables, fruits, and whole grains. These fibres are so complex that our stomach cannot digest them and only the bacteria present in our intestines can extract a small amount of their sugar content.
The main difference between the various types of carbohydrates is how fast they are absorbed by the intestine and transported into the bloodstream. In the case of simple sugars, their rapid assimilation forces the pancreas to react by secreting a large amount of insulin. Conversely, in the case of dietary plant fibres or complex starches, the intestine breaks down these sugars much more slowly, causing sugar to appear gradually in the blood and produce less insulin. To distinguish the effects of carbohydrates on blood glucose, we use the concepts of glycemic index and glycemic load.
Ingesting a food with a high glycemic load, such as corn flakes, rapidly increases the blood glucose level, which is accompanied by a massive secretion of insulin striving to absorb all the sugar. However, it may happen that the amount of insulin produced by the pancreas in response to this sugar level is too great, which can result in excessive glucose absorption, and paradoxically, a hypoglycemic state a few hours after eating a meal. This is not a desirable outcome as the lack of glucose in the blood greatly stimulates the centres involved in appetite control, causing a craving for more food to raise the glucose level. If repeated excessively, these fluctuations will not only wear out the pancreas but also promote obesity. Actually, insulin helps convert sugars into fats, as well as store them in the adipose tissues.
Conversely, consuming foods containing complex carbohydrates (with a low glycemic load, such as whole grain products and legumes) produces a much smaller amount of glucose and insulin in the blood. Under these conditions, the glycemia is stabilized over a longer period, without hypoglycemic episodes. By avoiding blood glucose fluctuations, this type of carbohydrate reduces insulin production and prevents overloading of the pancreas. In addition to being important for diabetics or pre-diabetics, who must maintain a stable glycemic level, consuming complex carbohydrates with a low glycemic load is a dietary change that can have a big impact on diabetes prevention in general.
###
The study received funding from the National Institutes of Health’s National Center for Advancing Translational Sciences and from Australia’s National Health and Medical Research Council.
About LA BioMed
Founded in 1952, LA BioMed is one of the country’s leading nonprofit independent biomedical research institutes. It has approximately 100 principal researchers conducting studies into improved treatments and cures for cancer, inherited diseases, infectious diseases, illnesses caused by environmental factors and more. It also educates young scientists and provides community services, including prenatal counseling and childhood nutrition programs. LA BioMed is academically affiliated with the David Geffen School of Medicine at UCLA and located on the campus of Harbor-UCLA Medical Center.
###
Laura Mecoy
.(JavaScript must be enabled to view this email address)
310-546-5860
Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center (LA BioMed)