Diabetes: Sleep Apnea Increases Risk of Amputation, Blindness In Diabetics

PEOPLE with Type 2 diabetes who have obstructive sleep apnea (OSA) are more at risk of losing their sight due to severe retinopathy, as well as foot problems and possible amputation because of neuropathy, according to new research in the UK.

Retinopathy affects the blood vessels supplying the retina – the seeing part of the eye. Blood vessels in the retina of the eye can become blocked, leaky or grow haphazardly. This damage gets in the way of the light passing through to the retina and if left untreated can damage vision.

Neuropathy is nerve damage and a long term complication of diabetes that can lead to foot ulcers and slow-healing wounds which, if they become infected, can result in amputation.

Obstructive sleep apnea (OSA) is a condition that causes interrupted breathing during sleep. The onset of OSA is most common in people aged 35 to 54 years old, although it can affect people of all ages, including children. The condition often goes undiagnosed. Only one in four people with obstructive sleep apnea are diagnosed with the condition.

(Image courtesy: HealthTree.com)

Dr Iain Frame, Director of Research at Diabetes UK, said: "We already know that there is a high prevalence of OSA in people with Type 2 diabetes. However, this is the first time that the link between OSA and retinopathy and neuropathy in people with Type 2 diabetes has been examined.

This research suggests that if someone with Type 2 diabetes also has this sleeping disorder they are more at risk of developing these serious complications compared to someone with the condition who does not have OSA.

"As being overweight is a risk factor for both OSA and Type 2 diabetes, this is yet another reason to highlight the importance of good weight management through a healthy diet and regular physical activity. In people with Type 2 diabetes, the increasing severity of OSA is associated with poorer blood glucose control and the treatment of sleep disorders (in this case by losing weight) has the potential to improve diabetes control and energy levels."

Researchers from the University of Birmingham looked at 231 people with Type 2 diabetes of whom 149 had OSA, a sleep disorder caused by disturbed breathing. They found there were twice as many people with severe retinopathy (48 percent) in the group with OSA compared to the group without OSA (20 percent). Retinopathy is the leading cause of blindness in the UK's working-age population.

In a separate study, the researchers found that OSA was also linked to neuropathy. They looked at 230 people with Type 2 diabetes of whom 148 had OSA. They found that 60 percent of the group with OSA also had neuropathy compared to 22 percent in the group without OSA.

In both studies, the association between OSA and the two diabetes complications in people with Type 2 diabetes was independent of age, gender, ethnicity, blood pressure, blood glucose levels, smoking and cholesterol.

Dr Abd Tahrani, who led the research, said: "Our work highlights several important issues. Our results emphasized what is already known - that OSA is very common in patients with Type 2 diabetes, much higher than OSA prevalence in the general population.

"Furthermore, our results suggest that OSA is not an innocent bystander in patients with Type 2 diabetes and might contribute to morbidities associated with this condition. Whether OSA treatment has any impact on these complications will need to be determined"

Source: Diabetes UK

Mystery Mechanism Protects Some Diabetics From Developing Complications

WHY are some diabetics free of complications? Researchers are now asking the question the other way around. They want to know why some diabetic patients do not develop complications. What is protecting them? It seems some people with diabetes possess yet-unidentified factors that reduce the risk for and even prevent them from developing diabetes-related complications, despite living with the disease for decades. If researchers can identify the mechanisms protecting these individuals ‒ who are clearly different because something protects them from devastating complications ‒ then it might be possible to develop drugs that can do the same thing.

I had reported end January that what current research provides is an admission that the fundamental mechanisms that create the environment for the development of diabetes complications are still very much unknown.

One aspect of the disease though that is very well documented is the damage that the disease wreaks on an individual’s blood vessels. Diabetes does not kill the individual but the complications often do.

Among the top of the list of complications is cardiovascular disease, as diabetics have three times of the risk compared to non-diabetics. The small blood vessels are also damaged. Nearly 70 percent of patients would have suffered from kidney damage leading to end stage renal failure. Many others suffer from eye complications, with nearly two percent of these diabetics going blind eventually.

Still, despite decades of intensive research on diabetes complications, the fundamental mechanisms are not yet fully known. Neither it is possible to prevent or treat the damage of the blood vessels that affects a majority of all diabetics.

“The blood vessels and other organs of the body are sugar coated and become stiff. It is reminiscent of a premature biological aging,” says Peter Nilsson of the Lund University Diabetes Centre in Sweden who isstudying diabetics with no complications in Sweden.

A just-published study conducted by the Joslin Diabetes Center on people who have lived with type 1 diabetes for more than 50 years presents a strong case for the existence of a protective mechanism in some individuals that allows them to live relatively free of the problems typically associated with long-term duration of diabetes. These mechanisms, the study found, may be different for microvascular (such as kidney, nerve and eye disease) than macrovascular complications (such as heart disease).

A press release issued by the American Diabetes Association yesterday quotes lead researcher George King, Chief Scientific Officer of the Joslin Diabetes Center and Professor of Medicine at Harvard Medical School saying: "If we can identify what constitutes this protective mechanism, we have the potential to induce such protections in others living with diabetes…That's huge."

The Joslin researchers looked at 351 U.S. residents known as the "Medalist" cohort and found that a subgroup of people who had lived with type 1 diabetes for more than 50 years remained free from such complications as proliferative diabetic retinopathy (PDR), a serious eye disease that can lead to blindness (42.6 percent of them); nephropathy, or kidney damage (86.9 percent of them); neuropathy, or nerve damage (39.4 percent); and cardiovascular disease (51.5 percent). Of those who did not develop PDR, 96 percent with no retinopathy progression in the first 17 years of their disease never experienced a worsening of symptoms, meaning that they likely possessed some type of protection specific to this complication.

Surprisingly, glycemic control was not a factor in providing this protective mechanism.

"That doesn't mean of course that glycemic control doesn't help to prevent complications. Numerous other studies have shown that it unquestionably does. In this case, it means only that there is a separate, protective mechanism in play that is not related to glycemic control that also helps to protect against diabetes-related problems. We are still working on identifying just what that is," King said.

It's important to note that most of the people in this study developed type 1 diabetes before strict glycemic control was even possible or used as the standard of medical care, the researchers write. The people in this study likely lived for several decades, therefore, without maintaining strict control.

The study also found that those with high plasma carboxyethyl-lysine and pentosidine, or advanced glycation end products (AGEs), were 7.2 times more likely to have some kind of complication than those who had low levels of this combination of AGEs. (AGEs are compounds that develop in the body after long exposure to high glucose levels and have generally been regarded as playing a role in diabetes-related complications.)

However, those with other types of AGE molecules exhibited protective features. Thus, this study suggests that not all AGEs are alike in their actions and raises the exciting possibility that some AGEs may be markers for protection against one or more diabetic complications.

In an accompanying editorial titled The Question Is, My Dear Watson, Why Did the Dog Not Bark?, Dr. Aaron Vinik, Director, Eastern Virginia Medical School Diabetes Research Center, writes that "the accumulation of AGEs may be one of the important factors in metabolic memory," a phenomenon in which an initial period of good glycemic, lipid and blood pressure control results in a prolonged period of health benefits that last beyond the period of control.

However, while it is clear that for some there is a protective mechanism at play, it's unclear whether metabolic memory is playing a role because glycemic control was not considered important until 1993, long after the study began.

What's most interesting, Vinik points out, is that sRAGE (the circulating soluble receptor for AGEs) is deficient in those who have the most severe complications, and is present at high levels in those with the most longevity. "If this is the missing link, it is huge for the possible emergence of a new biomarker and the potential for therapy that might increase circulating sRAGE or sRAGE itself," he said.

Hearing Loss Under-Recognized Complication of Diabetes

Hearing loss is about twice as common in adults with diabetes compared to those who do not have the disease, according to a study funded by the National Institutes of Health (NIH) and published in the Annals of Internal Medicine.

Diabetes may lead to hearing loss by damaging the nerves and blood vessels of the inner ear, research suggest. Autopsy studies of diabetes patients have shown evidence of such damage. (See my earlier post 'Diabetes and Hearing Loss' here.)

Yet hearing screenings typically are not part of the regular regimen of care that people with diabetes are routinely recommended to receive. Nor do the vast majority of doctors in today’s health care system include hearing health as a routine part of annual exams.

Hearing loss is one of the most commonly unaddressed health conditions in America today, and affects more than 34 million Americans. Six out of ten Americans with hearing loss are below retirement age.

"Hearing loss affects virtually every aspect of a person's life, making it all the harder for people with diabetes to cope with their disease,” says Sergei Kochkin, PhD, the Better Hearing Institute 's executive director. “A hearing check is invaluable in determining whether or not someone with diabetes does have a hearing loss and will help to ensure that they get the treatment they need."

"Hearing loss may be an under-recognized complication of diabetes. As diabetes becomes more common, the disease may become a more significant contributor to hearing loss," says senior author Catherine Cowie, Ph.D., of the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), who suggests that people with diabetes should consider having their hearing tested. "Our study found a strong and consistent link between hearing impairment and diabetes using a number of different outcomes."

[In fact, recent research, reported this month in the American Journal of Kidney Disease, found persons suffering from moderate chronic kidney disease (a complication attributable to diabetes as well) are likely to have hearing loss and should receive regular screenings. Specifically the study found 54.4 percent of all the patients in the study with moderate CKD had some degree of hearing loss.]

Adults with pre-diabetes, whose blood glucose is higher than normal but not high enough for a diabetes diagnosis, had a 30 percent higher rate of hearing loss compared to those with normal blood sugar tested after an overnight fast.

Besides, numerous studies have linked untreated hearing loss to a wide range of physical and emotional conditions, including irritability, negativism, anger, fatigue, tension, stress, depression, avoidance or withdrawal from social situations, social rejection and loneliness, reduced alertness and increased risk to personal safety, impaired memory and ability to learn new tasks, reduced job performance and earning power, and diminished psychological and overall health.

BHI is highlighting the connection between diabetes and hearing health and is urging all Americans to take the Diabetes Risk Test and the Across America Hearing Check Challenge onAmerican Diabetes Association Alert Day℠. This year, Diabetes Alert Day is on March 22 and kicks off the "Join the Million Challenge"—a month-long effort to rally one million people to take the Diabetes Risk Test by April 22 to find out if they are at risk for developing type 2 diabetes.

"Diabetes Alert Day is a tremendously valuable initiative because it prompts people to take a simple Diabetes Risk Test and to make changes in the way they live so they can preserve their health," said Kochkin.

"It's also important that people with diabetes understand that they may be at an increased risk of hearing loss as a result of their disease. We urge anyone with diabetes to take the Across America Hearing Check Challenge, a quick and confidential online hearing test to determine if they need a comprehensive hearing check by a hearing professional."

[The American Diabetes Association Alert Day℠ is a one-day "wake-up" call to inform the American public about the seriousness of diabetes. The American Diabetes Association (ADA) encourages people to join the movement to Stop Diabetes by taking the Diabetes Risk Test to find out if they, or their loved ones, are at risk for developing type 2 diabetes.

To become part of the movement to Stop Diabetes and get a free Diabetes Risk Test (English or Spanish), individuals can visit stopdiabetes.com, call 1-800-DIABETES (1-800-342-2383) or text JOIN to 69866 (Standard data and message rates apply). Although Diabetes Alert Day is a one-day event, the Diabetes Risk Test is available year round.]