Obstructive sleep apnea (OSA) impairs brachial artery endothelial function to a similar degree to Type 2 diabetes, show study results.

Atul Malhotra (Brigham and Women’s Hospital, Boston, Massachusetts, USA) say that treatment of OSA in Type 2 diabetes patients has the potential to improve macro- but not microvascular outcomes, as they found that OSA does not appear to influence brachial endothelium-independent vasodilation or skin microcirculation.

The investigators recruited 153 individuals with a mean age per subgroup ranging from 33 to 59 years. These included 14 healthy normal-weight controls, 33 healthy obese controls, 66 individuals with Type 2 diabetes, and 38 obese individuals with OSA.

The team notes that the diabetic participants and normal-weight controls did not undergo sleep testing for OSA and therefore could have had subclinical OSA.

As reported in the journal Obesity, the researchers found that patients with Type 2 diabetes and OSA had impaired flow mediated dilation (FMD), as assessed by brachial artery ultrasound, compared with normal-weight and obese controls, at 5.8% and 5.4% versus 9.1% and 8.3%, respectively.

Further analysis showed that baseline brachial artery diameter, OSA, and Type 2 diabetes status were significant negative predictors of percentage FMD.

However, OSA did not significantly affect skin microcirculation, as assessed by laser Doppler flowmetry, or nitroglycerin-induced vasodilation of the brachial artery.

“To our knowledge, this is the first study to compare endothelial function between OSA and Type 2 diabetes,” write Malhotra et al.

“These findings represent an important addition to the literature and will be critical to the design of subsequent interventional diabetes studies.”

They conclude: “Future research in the interacting vascular complications of diabetes mellitus and OSA populations may provide new therapeutic options for afflicted patients.”

MedWire (www.medwire-news.md) is an independent clinical news service provided by Current Medicine Group, a trading division of Springer Healthcare Limited. © Springer Healthcare Ltd; 2010

Free abstract

When people with type 2 diabetes are advised on how to control their diabetes… the type of food they eat and the amount of exercise they should do each week, predominates in the conversation. Up until now sleep is usually not mentioned but according to research, sleep might be another important factor.

A study at the University of Chicago looked at sleep and glucose tolerance in eleven non-diabetic people, average age 40, who were overweight and under-exercised. They averaged slightly less than eight hours of sleep each night.

• for fourteen nights they were allowed to sleep for eight and a half hours, and
• for fourteen nights they were allowed to sleep only five and a half hours
• no exercise was permitted, and
• junk food was provided

During the two weeks of being sleep deprived, the volunteers had higher blood sugar levels and showed less sensitivity to insulin.

Another study at the same institution found similar results in younger, leaner volunteers. Nine people between the ages of 21 and 30 were allowed to sleep for eight and half hours for three nights in the lab. When the subjects went into deep sleep, sound was used to make them sleep more lightly. A glucose tolerance test was given and blood insulin levels were measured. It was found that sensitivity to insulin decreased by 25 per cent. In eight of the subjects, insulin production did not increase, causing their blood sugars to rise by 23 per cent.

Sleep apnea, or stoppage of breathing for 10 seconds or more during sleep, is common among diabetics. About 40% of men with type 2 diabetes also suffer sleep apnea, and that number goes up to 61 per cent for men over 65.

Lack of sleep or at least deep sleep, may cause imbalances in substances like catecholamines and the hormone cortisol in your body. Catecholamines and cortisol prepare your body for the ‘fight or flight’ response, and one way they do this is by raising the blood sugar level. This is one possible mechanism for a connection between lack of quality sleep and type 2 diabetes.

Like type 2 diabetes, sleep apnea is a disorder that people who have it, often don’t recognize.

Symptoms include:

• tiredness
• waking up tired
• lack of energy
• headaches, and
• falling asleep without trying to, such as when reading or watching television.

A lack of quality sleep places you at an increased risk of several health problems. If you are type 2 diabetic it will make weight loss and control of your blood sugar levels much more difficult. Not getting enough sleep on a regular basis makes your body less sensitive to insulin which puts you at an increased risk of weight gain.