Obstructive sleep apnea, CPAP therapy, and diabetes

This study involved a large population of veterans diagnosed with obstructive sleep apnea (OSA). The study authors examined CPAP therapy usage and its effect on diabetes. The results showed that metabolic markers of diabetes were reduced in those patients that used the CPAP the most per night. Specifically, usage of at least 6 hours per night. The reduction in diabetes markers was not present in those with less nightly CPAP usage. Also, the risk of developing diabetes was reduced by those that used CPAP at least 6 hours per night. Finally, both of these findings were not influenced by the slight increase in weight observed during the follow up period measured.

Sleep deprivation and insulin

More research continues to be done on the effects of sleep deprivation on our metabolism. This article summarizes a small study looking at how acute sleep loss impacts insulin sensitivity. Researchers studied healthy, young adults without diabetes. They reduced their sleep time from 9 to 5 hours for five nights in a row - supposedly to simulate how little some may sleep during a workweek. After the 5 short nights, they let the participants sleep 9 hours a night for five more nights. The results showed that the subjects sensitivity to insulin decreased during the 5-hour sleep nights. This means that their bodies had to produce more insulin to keep their blood sugar under control. They didn't develop diabetes, but reduced insulin sensitivity is a precursor to diabetes. The next step will be to assess how less sleep affects older adults and adults with pre-diabetes / diabetes.

CPAP and blood sugar levels in Prediabetes

Prediabetes is a condition in which blood sugar levels are elevated above normal, but not high enough to meet criteria for diabetes. Here is a study that measured blood sugar levels (and other parameters) during two weeks of CPAP use versus an oral placebo in patients diagnosed with obstructive sleep apnea. I only have access to the abstract and an article about the study. In this study, researchers ensured that those randomized to CPAP used it for 8 hours a night for two weeks straight. The results showed that the CPAP users had lower blood sugar levels as the main outcome. A secondary outcome measure showed lower blood pressure levels in the CPAP users when compared to the controls.

Sleep-disordered breathing in pregnancy

I've blogged before here, here, and here about pregnancy and breathing disorders in sleep. We know that the prevalence of sleep-disordered breathing (SDB) symptoms increases the further along in the pregnancy. This could be due weight gain and swelling that occurs as pregnancy progresses.

Some studies have shown an association between SDB and pregnancy-related illnesses like high blood pressure, gestational diabetes, and pre-term birth. However, many of these studies relied on subjective assessment of SDB. This study was done to look at the relationship of objectively assessed SDB and certain pregnancy-related illnesses. A home sleep study was performed on pregnant women twice - once between 6 - 20 weeks and again between 28 - 37 weeks. Results showed that 30% of the pregnant women had SDB early pregnancy. However, there was no relationship between SDB and maternal high blood pressure (called preeclampsia), preterm birth, or extremes of birthweight (low or high). There was a relationship between SDB severity and risk of developing gestational diabetes, even after controlling for confounding factors like age, race, body-mass index, hx of chronic high blood pressure, etc.

Despite the observed relationship between sleep-disordered breathing and gestational diabetes, the study authors pointed out that there is no evidence that treatment of the SDB in the short term improves maternal or neonatal outcomes.

CPAP improves blood sugar control

I've blogged before about how patients with obstructive sleep apnea (OSA) are at increased risk of developing diabetes. I've also written about how treating OSA can improve blood sugar control in diabetics. Here is another study that demonstrates long term use of CPAP (5 years) is associated with better control of blood sugar in diabetics. The study also showed that long term use of CPAP was associated with lower blood pressure and improved quality of life. The study authors concluded that CPAP use is a cost-effective treatment option for OSA.

Blood sugar and fat metabolism in narcoleptics treated with sodium oxybate

Narcolepsy is a neurological disorder characterized by excessive sleepiness. It's caused by destruction of a group of neurons in a part of our brain called the hypothalamus. The hypothalamus is important in regulating our hormones, many of which control basic functions like sleep and hunger. Because of the location in the brain, reports have linked narcolepsy to elevated weight and even type 2 diabetes. It's been theorized that patients with narcolepsy have reduced sensitivity to insulin, much like type 2 diabetics.

This study was done to assess both blood sugar and fat metabolism in a small group of narcoleptics and compared them to a matched control group that did not have narcolepsy. They used a sophisticated test to measure both fat and blood sugar metabolism, something that had not been done before in older studies of patients with narcolepsy. The results were interesting in that the researchers found that narcoleptics had increased insulin sensitivity in the periphery - the opposite of what they expected. Liver cell insulin sensitivity and pancreatic function were the same as matched controls. Fat metabolism tended to be lower in patients with narcolepsy, which may explain in part why narcolepsy is linked with being overweight.

The researchers also treated the narcoleptic patients with sodium oxybate, a medicine that improves some of the narcolepsy symptoms. It's taken at night, and improves the patients' sleep quality, although it's not a sleep aid. Interestingly, the sodium oxybate increased fat metabolism, and the narcoleptic patients lost an average of 5.2 kg (11.5 pounds) in the three months of the study. The exact mechanism of the weight loss is not known.

The bottom line is that the results of this study do not support an increased risk of type 2 diabetes in narcoleptics. Also, patients with narcolepsy that are treated with sodium oxybate may lose weight, although the exact mechanism is unclear.

Sleep loss and metabolic syndrome

Metabolic syndrome is a chronic disorder characterized by abdominal obesity, impaired blood sugar metabolism, high cholesterol, and high blood pressure. Here is an article about sleep loss and it's affect on our metabolism. The article is a review of the observational studies that examine the relationship between sleep deprivation and metabolic syndrome. The authors discuss some of the studies that show that acute sleep loss is linked with obesity, type 2 diabetes, cholesterol problems, high blood pressure, and even death. Of note, some of the studies show increased rates of some of these issues when people report sleeping less than or more than a specified "normal" amount of sleep. So it's not just sleep loss that is linked to problems, including mortality.

The authors note that sleep loss can affect appetite, food intake, physical activity levels, and energy expenditure. Again, these are short term studies and the reasons for the changes are not entirely clear. Results sometimes are conflicting, such as some studies showing higher levels, and other studies showing lower levels of appetite regulating hormones.

The authors conclude that sleep loss may be a "promising target for the prevention, and probably the treatment, of the metabolic syndrome and its components." Perhaps that is the case, but telling people to get more sleep is unlikely to improve their metabolic syndrome. It's certainly more complicated than that. Diet and exercise are just as important, and most likely much more so than just getting more sleep. I concede that insufficient sleep may contribute a small part to metabolic syndrome, but more long term studies are needed. And I agree with the authors when they conclude that ongoing and future studies will show whether interventions to improve sleep duration and quality can prevent or even reverse adverse metabolic traits."

Blood sugar control and obstructive sleep apnea

Human sleep can be divided into two different stages, non-REM sleep and REM sleep. During REM sleep is when most dreaming occurs. And while we dream, our brain temporarily paralyzes our muscles to minimize potential harm that would occur if we acted out the dreams we had. However, when the throat muscles get paralyzed in REM sleep, the throat becomes even more floppy, and obstructive sleep apnea (OSA) can be more severe. In some patients, the difference in OSA severity from NREM to REM is quite striking - some patients have OSA confined almost exclusively to those periods of REM sleep.

Some sleep researchers feel that OSA confined only to REM sleep may not be as serious as OSA that is present in both stages of sleep, as I have blogged about before. But in my experience, patients that treat their REM sleep-related OSA often have an improved quality of life.

This article showed that the more severe the OSA is in REM sleep, the worse control of diabetes. It's not clear why that would be, but the findings do not support the thinking that REM sleep OSA is less serious. The study authors point out that since most REM sleep occurs in the second half of the night, patients who don't use their CPAP all night may be at greater risk of having less control of their blood sugars.

Gestational diabetes and obstructive sleep apnea

Gestational diabetes refers to having high blood sugars during pregnancy. Sometimes it is associated with excess weight gain during pregnancy.

This article discusses research showing that pregnant women with gestational diabetes are nearly seven times more likely to have obstructive sleep apnea (OSA) than other pregnant women. Also, the women who did not have gestational diabetes got an additional hour of sleep and had less broken up sleep than women who had gestational diabetes.

The researchers suggested that women who have gestational diabetes consider getting evaluated for OSA.

Diabetics and those with high blood pressure should be tested for obstructive sleep apnea

Here is an article from the annual sleep meeting last week. The American Academy of Sleep Medicine recommends evaluation for patients with high blood pressure and type 2 diabetes, since they are at increased risk of having obstructive sleep apnea.

Weight loss in obese type 2 diabetics with obstructive sleep apnea

Obesity, type 2 diabetes, and obstructive sleep apnea (OSA) occur together commonly. Weight reduction has been shown to improve both blood sugar control and OSA severity. There is a study that looked at intensive lifestyle intervention (ILI) versus usual diabetic support (DS) in OSA severity. After one year, the ILI group had greater weight reductions and less severe OSA than the DS group. The researchers then looked at the results after 3 more years, as reported in this paper.

So after the first year, the intensive lifestyle intervention was provided on an individual basis and included one on-site visit per month. There was a second contact by telephone, regular mail, or email. At each session, participants were weighed, self-monitoring records reviewed, and a new lesson presented. The usual diabetes support group had three annual sessions, with each one focusing on diet, physical activity, and social support. Information on behavioral strategies was not presented and participants were not weighed, like in the ILI group.

Results showed that at year 4, >5 times as many participants in the ILI group had total remission of their OSA. The prevalence of severe OSA among ILI group was half that of the diabetes support group. OSA remission occurred in those with mild to moderate OSA at baseline. But in those with severe OSA at baseline, none achieved remission and few changed to mild severity. And in both groups, a similar prportion had a worsening of OSA severity at year 4. Some had mild OSA at baseline and then severe OSA at year 4! A limitation of this study is that almost 38% of participants dropped out by year 4, primarily due to not wanting to repeat PSG.

So what does all this mean? That if you have severe OSA, weight reduction alone is unlikely to get rid of the OSA. However, weight reduction alone may eliminate OSA that is mild to moderate.

Type 2 diabetes linked to low melatonin levels

Melatonin is the hormone produced in your brain when the sun goes down. It is the signal that says it's time for sleep soon. This article talks about a study that showed that people with low amounts of melatonin at night were twice as likely to develop type 2 diabetes.

It will be interesting to see if taking melatonin would prevent people who are at risk from developing diabetes. Research also needs to be done to figure out how and why melatonin is related to diabetes. I wonder if people with type 1 diabetes also have low melatonin levels at night.

Diseases that are more common in people with obstructive sleep apnea

Here is a study in the Journal of Clinical Sleep Medicine out of Denmark that analyzed which diseases were more common in patients later diagnosed with obstructive sleep apnea (OSA). The researchers used 1% as the cutoff off for inclusion. The results showed that in those diagnosed with OSA, their was an increased risk of the person having already been diagnosed with diabetes, hearing loss, high blood pressure, angina, atrial fibrillation, pneumonia, emphysema, asthma, deviated nasal septum, and prostate enlargement. These make sense clinically, and many of the conditions co-exist. Obesity is a common factor in OSA, and this could link some of the conditions listed.

The hearing loss is interesting, and may be related to loud snoring. Deviated nasal septum could impact airflow through the nose, increasing snoring and OSA. OSA can increase night time urination. In men, they might get diagnosed more with prostate enlargement when they report this nighttime urination. But their doctor may not think about OSA as a cause until later.

Obstructive sleep apnea damages cardiovascular system to same extent as diabetes

Obstructive sleep apnea (OSA) has been linked to higher rates of cardiovascular disease. This study looked at a small number of patients with moderate to severe OSA. In particular, they studied their cardiovascular systems using sophisticated imaging equipment, and compared the findings to diabetics without OSA. The results showed that both OSA and diabetes causes a similar amount of damage to the cardiovascular systems

Sleep apnea can increase risk for type 2 diabetes

This article discusses research showing that obstructive sleep apnea (OSA) may increase risk for type 2 diabetes - which is typically adult onset and often linked to obesity. However, researchers studied healthy young men and measured their insulin sensitivity and insulin levels. In those men with OSA, they showed signs of reduced insulin sensitivity and increased insulin levels, which are precursors to diabetes. Now the article does not state whether the patients with OSA were treated.

Obstructive sleep apnea is linked to decreased insulin resistance.

This article describes research showing that children with obstructive sleep apnea have decreased sensitivity to insulin. Decreased sensitivity to insulin can be seen in diabetes. The researchers hypothesized that oxygen level decreases seen in obstructive sleep apnea could be responsible for the decreased sensitivity to insulin. Results of this study suggest that it is important to screen patients with diabetes or who are prediabetic for obstructive sleep apnea.

Insomnia, obstructive sleep apnea, or daytime sleepiness is linked to insulin resistance

This article discusses research showing that patients with insomnia, obstructive sleep apnea (OSA), or excessive daytime sleepiness are more likely to have insulin resistance. This is no surprise to me, as research has shown a link between OSA and diabetes before. But this research may prompt primary care physicians to test their patients for diabetes if they also experience insomnia or daytime sleepiness, or have known OSA.

Obstructive Sleep Apnea severity and Diabetes Marker

This article discuss research findings showing that obstructive sleep apnea (OSA) severity is linked to hemoglobin A1C (HgbA1c), a marker for diabetes severity. The more severe the OSA, the higher the HgbA1c. This comes as no surprise as we have known about an association between untreated OSA and diabetes.

Women with polycystic ovarian syndrome and obstructive sleep apnea more likely to have prediabetes

This article discusses how women with a condition called polycystic ovarian syndrome (PCOS) and obstructive sleep apnea (OSA) are at increased risk of being prediabetic. See my other blogpost about OSA and PCOS.

Obstructive Sleep Apnea and Diabetes

Here is an article about data presented at the American Thoracic Society linking obstructive sleep apnea (OSA) to type 2 diabetes. This study confirms what we already think clinically about OSA and diabetes.