An experiment in science writing — is simpler better?
Take a look at these two articles. Both of them describe a paper from researchers in Grenoble, France, who are studying the effects of sleep apnea on metabolism. One is shorter and simpler, with more bolded subheads, and the other is longer and includes links and quotes from one of the researchers. Which one do you prefer, Article A or Article B?
Article A
Simulation of sleep apnea can push the body into early signs of type 2 diabetes
Obstructive sleep apnea and type 2 diabetes often come together in the same person. More than half of people with type 2 diabetes also have OSA. That makes sense, because both conditions can be thought of as consequences of obesity.
On the surface, we might think of type 2 diabetes as a problem with hormones and regulation of blood sugar (glucose), and sleep apnea as a problem with breathing. But there is a physiological link between the two conditions. A recently published study from Grenoble, France shows how that connection works.
Like hiking in the Himalayas, but in the hospital
The French researchers exposed young, slim people to conditions that simulate the effects of sleep apnea. The volunteers slept in special tents in the hospital, exposing them to low-oxygen conditions. While they slept, they had tubes under their noses that gave them oxygen every two minutes. This meant that the level of oxygen in the volunteers’ blood went down and up throughout the night, even though they didn’t actually have sleep apnea.
After sleeping under these conditions for two weeks, the volunteers had very early signs of type 2 diabetes, but not the full-blown metabolic disorder. Specifically, they showed signs of insulin resistance.
Type 2 diabetes affects the body’s use of both sugar and fat
Insulin resistance is a central feature of type 2 diabetes: the body continues to make insulin, the hormone that signals cells to take up blood sugar, but it doesn’t “listen” to the hormone. As a result, blood sugar can build up. Type 2 diabetes is in turn linked with a host of complications, like nerve or eye damage, as well as heart disease and kidney disease.
After their low-oxygen sleeping experiences, the people in the French study didn’t have higher levels of blood sugar. However, they had more fatty acids in their blood in a test that is sometimes used to diagnose type 2 diabetes, called a glucose tolerance test.
This result is similar to previous studies showing that a period of bed rest (lying in bed all day for a couple weeks) OR sleep deprivation (getting just 6 hours of sleep) can also reduce the body’s sensitivity to insulin in otherwise healthy people. In the same way as sleeping in low oxygen, the bed rest or sleep deprivation gives the body a nudge in the direction of type 2 diabetes.
The bottom line
What does this mean for you? If you have obstructive sleep apnea, you should be talking with your doctor about your risk of type 2 diabetes and how to treat or prevent it. This research also helps us understand how low-oxygen conditions perturb the body’s regulation of hormones.
Article B
Simulation of sleep apnea can push the body into early signs of type 2 diabetes
Obstructive sleep apnea and type 2 diabetes often occur together. More than half of people with type 2 diabetes also have OSA. That makes sense, because both conditions can be thought of as consequences of obesity.
On the surface, we might think of type 2 diabetes as a problem with hormones and regulation of blood sugar (glucose), and sleep apnea as a problem with breathing. However, a recently published study from France demonstrates a physiological link between the two conditions, and provides clues on how one causes the other.
Exposing young, slim people to intermittent hypoxia for two weeks can induce signs of lipid insulin resistance, this study found. Intermittent hypoxia means periods of time when the study participants were breathing air with low oxygen levels.
After being exposed to intermittent hypoxia, study participants had more free fatty acids in their blood under conditions sometimes used to diagnose type 2 diabetes: a glucose tolerance test. This is an early sign of insulin resistance, a central feature of type 2 diabetes.
This means that when the body is challenged by low oxygen, mechanisms that push the body toward type 2 diabetes are working — even in non-overweight people who don’t have sleep apnea.
“We believe that these mechanisms triggered by intermittent hypoxia are the first steps involved in the development of insulin resistance observed in patients with OSA,” the authors concluded in their paper.
“While we did not reproduce all aspects of OSA, our results strengthen our hypothesis that the same mechanism occurs in full OSA”, says lead author Anne Briancon-Marjollet, an associate professor at Université Grenoble Alpes. “Intermittent hypoxia is likely a strong player in the metabolic changes associated with OSA.”
Like hiking in the Himalayas, but in the hospital
The study participants slept in tents that surrounded them with a low-oxygen environment (oxygen was 13% of the atmosphere, instead of 21% normally), while wearing cannulas that provided oxygen every two minutes. This allowed the oxygen saturation level in their blood to periodically drop below 90%.
“It was like sleeping in a tent for hiking, but in the hospital”, Briancon-Marjollet says.
Her colleague and co-author Renaud Tamisier’s HP2 lab (Hypoxia and cardiovascular and respiratory PathoPhysiology) has published several papers on this model of sleep apnea, starting in 2009. Their experimental regime does not impose physical blockages of breathing, but hypoxia exposure increased the number of arousals: interruptions of sleep, as seen by EEG.
This study had a crossover design, such that part of the group slept under intermittent hypoxia conditions first, and others slept under normal conditions first, with at least four weeks in between. Participants did not know which group they were in. A total of 12 people started the study, but a few dropped out and 9 completed it. They had an average age of 22 and BMI of 22 kg/m2.
The impact of the intermittent hypoxia was limited, in that it did not elevate study participants’ blood pressure or change their fasting levels of glucose, insulin, cholesterol or triglycerides.
“We expected to see an effect on glucose levels, but didn’t see it,” Briancon-Marjollet says, adding that it’s possible that longer exposure to hypoxia might have such effects.
The researchers were able to gain insight into how intermittent hypoxia perturbs hormone regulation. Periodic low oxygen activated the sympathetic nervous system in the volunteers. This in turn activated lipolysis, when adipocytes (fat cells) break down lipids into their building blocks.
Other mechanisms could also be playing a role in the link between obstructive sleep apnea and type 2 diabetes, such as inflammation. This type of effect has previously been seen in animal experiments, but it’s more difficult for researchers to organize a study demonstrating the negative effects of intermittent hypoxia in humans.
The results are analogous to studies showing that a period of bed rest (lying in bed all day for a couple weeks) for otherwise healthy people can also reduce the body’s sensitivity to insulin — a nudge in the direction of type 2 diabetes, if not the full-blown disease. A period of sleep deprivation (getting just six hours of sleep for a few weeks) can have a similar effect.
“This condition does have strong implications for metabolic health,” Briancon-Marjollet says. “Physicians treating someone with OSA should be looking at its complications as well.”
Previous research has shown that CPAP therapy can lower blood glucose levels and reduce glycemic fluctuations in people with OSA and early signs of type 2 diabetes.
The backstory
I’ve been talking with Gilles Frydman, executive director of the American Sleep Apnea Association, about writing for their website sleephealth.org. We had the idea of doing a sort of “A/B test”. Both of these articles are aimed at people with sleep apnea. The first one is more streamlined “news you can use” style, while the second one has a bit more scientific information, lets the reader know who the French researchers are, and shows that I consulted them. Another way to perform an A/B test is to try each version one at a time, and see which one gets more engagement/clicks — but I’m not sure how to implement that. And it gets more complicated if I’d use various images to convey ideas connected with sleep apnea.
