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Update From the Medical Journals: June 2008 June 30, 2008 By Mary Pickett, M.D. What's the latest news in the medical journals this month? Find out what your doctor is reading.
Blood Sugar: How Low Is Too Low For Adults With Type 2 Diabetes? The New England Journal of Medicine published two important studies in its June 12 issue that looked at the health benefits of lowering blood sugar to near-normal levels in people with type 2 diabetes whose blood sugar was already controlled to the goal set by current diabetes guidelines. The first study, called the ACCORD trial, found that a group of people who received intensive treatment to lower blood glucose (sugar) below current recommendations unexpectedly had more deaths than a group of people who received treatment based on current diabetes care guidelines. The second study, called the ADVANCE trial, found that extremely tight blood sugar control (as compared to usual practice) had very little effect on the rate of heart or stroke complications and no measurable effect on survival. There was, however, a 21% lower rate of kidney disease in the intensively treated group. Both of these studies were large and carefully designed. Because of worrisome early results, part of the ACCORD study was stopped this past February, 18 months ahead of the planned study end date. The ACCORD trial, sponsored by the National Heart, Lung, and Blood Institute, involved 10,251 middle-aged and older adults with diabetes. All participants had atherosclerosis or risk factors for atherosclerosis. Blood-sugar averages were monitored using blood tests for hemoglobin A1C, a common diabetes monitoring test. The participants were randomly assigned to receive either intensive blood glucose-lowering treatment with enough medication to lower their hemoglobin A1C to under 6%, or more typical treatment to lower their A1C to 7% to 7.9%. The latter target goal is slightly more liberal than what the American Diabetes Association (ADA) advises, which is an A1C less than or equal to 7%. The first target goal would require nearly-normal blood sugars for diabetics. There were 257 deaths in the intensive-treatment group over an average of four years of treatment (ranging from about 2 years to about 7 years). There were 203 deaths in the treatment group with a more-typical blood sugar goal. This means that the risk for death was about 20% higher for those with a target blood-sugar goal of less than 6%. Many of the deaths appeared to be fatal heart attacks or strokes. The risk for a heart attack or stroke did not seem to be higher when non-fatal and fatal events were considered together. However, the risk for a fatal event did seem to be higher. The ADVANCE trial took place in Australia and included 11,140 people with type 2 diabetes. The desired A1C goal for the "tight control" group was 6.5%. (The other group had the current standard-of-care goal of 7%, and had an actual average A1C of 7.3%). Patients in both groups took a medicine from the sulfonylurea group (gliclazide) and both groups received additional medicines as needed when blood sugar averages were higher than the assigned goal. The study continued for five years. Prior studies suggested that reducing blood sugar of diabetic adults to levels found in non-diabetic adults may reduce the rate of some cardiovascular problems, such as heart attack. But the ADVANCE trial is the first study large enough to detect an effect on survival. Good blood-sugar control lowers the risk for damage to the eyes, kidneys and nerves. It can lower the risk for heart attack and stroke. These studies asked the question, "How low can you go?" The answer appears to be "not so low that your A1C is near normal," if you have type 2 diabetes and have an especially high heart-disease risk. For people who are young and at lower risk for heart complications, it is possible that a lower target might offer an advantage, since it lowers the risk of kidney disease. For most people, based upon these studies and prior data, control of blood sugar to an A1C level at or slightly beneath 7% is appropriate.
Bright Daytime Lighting Slows Progression of Dementia, Improves Quality of Life A unique study from the Netherlands offers a new strategy for improving symptoms of dementia. The study, published June 11 in the Journal of the American Medical Association (JAMA), was designed around the understanding that people who have dementia often have a diminished ability to track or react to day and night transitions — the 24-hour sleep-wake cycle also called circadian rhythms. Both light from the environment and the hormone melatonin, are necessary for normal circadian rhythms. The pineal gland, a small gland in the brain, makes melatonin in response to light signals from the eye. Researchers studied 189 residents in 12 assisted-care facilities, most of whom had dementia. Some residents received doses of bright light between 9 am and 6 pm, some took supplements of melatonin or placebo pills, and some received both treatments. A fourth group received no treatment. Almost all of the participants completed at least a year of the light and melatonin study, and researchers tracked their symptoms and compared groups. The results were exciting. People in the facilities with bright daytime lighting appeared to have less progression in their dementia. They had 53% less of a decline in physical function scores, and 5% less decline in memory test scores, compared with the average decline at dimly lit facilities. Those exposed to bright light were also 19% less likely to develop depression during the time of the study. People who took melatonin without bright light frequently complained of depression and were more likely to become socially isolated. This suggests that melatonin alone is not useful. However, when melatonin was given to the people who also had bright light exposure, depression rates were not higher than expected, and after several months of use, sleeping patterns seemed to improve. With both treatments, there was longer uninterrupted sleep, less frequent episodes when residents were up out of bed at night, and somewhat less agitated behavior. For people with dementia and for their caregivers, the use of bright lights is a simple, safe change. It may be helpful to combine light therapy with melatonin for people who have difficulty getting to sleep or staying asleep. This study could improve the quality of life for people with dementia and ease strain on those who care for them.
People Who Use NSAID Pain Medicines Have Less Risk For Alzheimer's Researchers published a report on the apparent link between non-steroidal anti-inflammatory drugs (NSAIDs) and a lowered risk for Alzheimer's disease. It appeared June 10 in the journal Neurology. Several previous studies found this link between pain medication and a lowered risk for Alzheimer's, but there has been disagreement about whether the association is real. There also has been speculation that one variety of NSAID might be more strongly associated with protection against Alzheimer's than others. This latest study combined and re-analyzed data from six previous studies that included a total of 13,499 people. This type of study is called a "meta-analysis." Because of the large number of people, researchers could compare different NSAIDS to each other, in terms of their association with lowered Alzheimer's risk. Since each person was first surveyed, 820 people developed new symptoms that met criteria for Alzheimer's dementia. People who regularly used NSAIDS had a 23% lower risk for developing dementia, compared with those who never used NSAIDS. The different NSAIDS (such as ibuprofen, naproxen and aspirin) all appeared to offer protection. Experts will look at this study with caution. A meta-analysis can provide faulty conclusions, because of a research problem known as publication bias. Studies that suggest an association between widely used drugs and Alzheimer's disease are more likely to be published in medical journals because they're more interesting than studies that find no connection. Of course, studies that are never published will be left out of a meta-analysis study. Consider how inaccurate the results of this meta-analysis study might be if in addition to the six studies included, there may have been six additional small studies done that found no connection, and were frankly too boring to be published. Studies like this meta-analysis tend to overestimate findings, but they do point out areas that are worth additional study. For now, there is inadequate evidence to recommend that people take NSAIDs in an effort to prevent Alzheimer's. NSAIDs are useful for treating pain, but they have potential side effects and should not be used more often than they are needed.
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