Next week’s meeting of the American Diabetes Association promises to deliver what could well be the most important medical news of the year: an understanding of the link between blood glucose control and cardiovascular disease.
Conventional wisdom and a number of observational studies have held that lowering blood glucose levels reduces risks of all sorts of vascular diseases, including cardiovascular diseases. But does the risk decrease in tandem with each drop in glucose measurement?
It’s a critical, life-and-death question. There are nearly 15 million Americans diagnosed with diabetes, and they are two to four times as likely to die of heart attack or stroke as people without diabetes, according to the ADA. Scientists are urgently looking for ways to improve those odds. Most professional medical groups recommend aiming for a score on the A1C test, which measures average glucose levels over two or three months, of 7% or lower.
The diabetes world was shocked in February when part of a huge clinical trial, called ACCORD, was halted early because scientists found that the type 2 patients in the study who were getting the most intensive treatment to reduce blood glucose levels – they were aiming for an A1C of 6% or less -- had higher rates of death than those getting standard treatments aimed an A1C of 7-7.9%.
Now, scientists will hear the details of ACCORD and two other major clinical trials, each with different A1C targets, that look at reducing cardiovascular deaths in patients with type 2 diabetes. In order of their presentation, they are:
• The ADVANCE Study, involving 11,140 patients with type 2 diabetes in 20 countries, is being presented at 2 p.m. PDT on Friday, June 6. Researchers at the George Institute in Australia announced in February that, in contrast to ACCORD, they saw no increased risk of death among patients who got aggressive treatment to lower blood glucose levels to an A1C of about 6.5%. They’ve already reported (in The Lancet, September, 2007) that strict control of blood pressure in one arm of the study achieved a reduction in death rates.
• The VA Diabetes Trial, which followed nearly 1,800 patients for seven years, wrapped up in May and final data will be presented on Sunday, June 8, at 4:15 p.m. PDT. Participants were divided randomly into groups that got treatments aiming for an average 6.5% A1C in the intensive-treatment group, or 8.5% for conventional treatment.
• The full story on ACCORD, sponsored by the National Heart Lung and Blood Institute, part of the U.S. National Institutes of Health, will be presented Tuesday morning, June 10, at 7:30 a.m. PDT.
Finally, and perhaps the most important session of the whole meeting, will be a panel of international diabetes experts convened Tuesday after the ACCORD presentation that will tease out the nuances of the three studies and try to come up with a take-home message to guide doctors and patients who are concerned about reducing heart risks associated with diabetes.
Whether that will be a clear and sharp message remains to be seen. Thanks to ACCORD, says Matt Petersen, ADA’s director of information resources, it can no longer be assumed that the tightest control of blood glucose is always best. All eyes will be on the panel that will assess the three studies to see what they conclude.
“We could either get a relatively good degree of clarity by the end of the day Tuesday or no clarity at all,’’ he says. The truth may emerge from the details, but “no matter how you slice and dice it, we won’t as readily be able to say lower (blood glucose) is always better.’’
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