Sleep apnea may increase insulin resistance

May 17, 2010

Sleep apnea may cause metabolic changes that increase insulin resistance, according to researchers from the University of Pittsburgh Medical Center. The intermittent hypoxia associated with sleep apnea causes a distinct drop in insulin sensitivity in mice, even though chronic hypoxia, such as that associated with high altitude, did not.

The research will be reported at the ATS 2010 International Conference in New Orleans.

To determine whether intermittent hypoxia (IH) and chronic hypoxia (CH) would have different metabolic effects, Dr. Lee and colleagues fitted adult male mice with arterial and venous catheters for continuous rapid blood monitoring of glucose and insulin sensitivity. They then exposed the mice to either seven hours of IH, in which treatment, oxygen levels oscillated, reaching a low of about 5 percent once a minute, or CH, in which they were exposed to oxygen at a constant rate of 10 percent, and compared each treatment group to protocol-matched controls.

When compared to the control group, the IH mice demonstrated impaired and reduced insulin sensitivity; the CH group, however, showed only a reduction in glucose tolerance but not insulin sensitivity compared to controls. "Both intermittent hypoxia and continuous hypoxia exposed mice exhibited impaired glucose tolerance, but only the intermittent hypoxia exposed animals demonstrated a reduction in insulin sensitivity," said Euhan John Lee, M.D., a fellow at the Medical Center.

"The intermittent hypoxia of sleep apnea and the continuous hypoxia of altitude are conditions of hypoxic stress that are known to modulate glucose and insulin homeostasis. Although both forms of hypoxia worsen glucose tolerance, this research demonstrated that the increase in that accompanies intermittent hypoxia, or sleep apnea, is greater than that seen with continuous hypoxia, or altitude," explained Dr. Lee.

The specific finding that intermittent, but not continuous, hypoxia induced insulin resistance was not expected.

Increased generation of reactive oxygen species, initiation of pro-inflammatory pathways, elevated sympathetic activity, or upregulation of insulin counter-regulatory hormones in IH may contribute to the greater development of insulin resistance in those mice versus those exposed to continuous hypoxia.

"As sleep apnea continues to rise with the rate of obesity, it will be increasingly important to understand both the independent and interactive effects of both morbidities on the development of metabolic disorders. This research demonstrated that intermittent hypoxic exposure can cause changes in insulin sensitivity and insulin secretion, which may have important consequences in metabolically vulnerable diabetic patients who present with co-morbid ," said Dr. Lee. "Future research will explore potential inflammatory and lipotoxic pathways by which intermittent hypoxia disrupts glucose and insulin homeostasis."

Explore further: Osteoporosis risk heightened among sleep apnea patients

add to favorites email to friend print save as pdf

Related Stories

Apelin hormone injections powerfully lower blood sugar

Nov 04, 2008

By injecting a hormone produced by fat and other tissues into mice, researchers report in the November Cell Metabolism that they significantly lowered blood sugar levels in normal and obese mice. The findings suggest that t ...

Recommended for you

Obese British man in court fight for surgery

Jul 11, 2011

A British man weighing 22 stone (139 kilograms, 306 pounds) launched a court appeal Monday against a decision to refuse him state-funded obesity surgery because he is not fat enough.

2008 crisis spurred rise in suicides in Europe

Jul 08, 2011

The financial crisis that began to hit Europe in mid-2008 reversed a steady, years-long fall in suicides among people of working age, according to a letter published on Friday by The Lancet.

New food labels dished up to keep Europe healthy

Jul 06, 2011

A groundbreaking deal on compulsory new food labels Wednesday is set to give Europeans clear information on the nutritional and energy content of products, as well as country of origin.

Overweight men have poorer sperm count

Jul 04, 2011

Overweight or obese men, like their female counterparts, have a lower chance of becoming a parent, according to a comparison of sperm quality presented at a European fertility meeting Monday.

User comments : 0

More news stories

Filipino tests negative for Middle East virus

A Filipino nurse who tested positive for the Middle East virus has been found free of infection in a subsequent examination after he returned home, Philippine health officials said Saturday.

Study says we're over the hill at 24

(Medical Xpress)—It's a hard pill to swallow, but if you're over 24 years of age you've already reached your peak in terms of your cognitive motor performance, according to a new Simon Fraser University study.

NASA's space station Robonaut finally getting legs

Robonaut, the first out-of-this-world humanoid, is finally getting its space legs. For three years, Robonaut has had to manage from the waist up. This new pair of legs means the experimental robot—now stuck ...

Ex-Apple chief plans mobile phone for India

Former Apple chief executive John Sculley, whose marketing skills helped bring the personal computer to desktops worldwide, says he plans to launch a mobile phone in India to exploit its still largely untapped ...

Egypt archaeologists find ancient writer's tomb

Egypt's minister of antiquities says a team of Spanish archaeologists has discovered two tombs in the southern part of the country, one of them belonging to a writer and containing a trove of artifacts including reed pens ...

Airbnb rental site raises $450 mn

Online lodging listings website Airbnb inked a $450 million funding deal with investors led by TPG, a source close to the matter said Friday.