In one large, ongoing trial of people with Type 2 diabetes and a high risk of cardiovascular disease, intensive blood glucose control has been linked with a slightly higher risk of death compared with less-intensive, "standard" treatment. Participants in the trial who were receiving intensive treatment will now be switched over to standard treatment. While these findings were unexpected and have raised some concerns about diabetes treatment strategies for specific groups of people, they should not trigger a change in therapy for most people with diabetes.
The study, known as the Action to Control Cardiovascular Risk in Diabetes (ACCORD) trial, is being conducted at 77 sites in North America. It has over 10,000 participants between the ages of 40 and 82 who have been involved with the study for between two and seven years. The participants all have Type 2 diabetes and especially high risk for heart attack and stroke, measured as having at least two risk factors for cardiovascular disease in addition to diabetes or as having been diagnosed with cardiovascular disease before the start of the study. The study was designed, in part, to test whether intensive blood glucose control would reduce the risk of heart attack, stroke, death from cardiovascular disease, and other “cardiovascular events” in this high-risk group.
The participants who were randomly assigned to the intensive control group aimed to lower their HbA1c levels (a measure of blood glucose over time) to less than 6%, or close to nondiabetic levels. In reality, half the participants in this group achieved an HbA1c level of less than 6.4%. Meanwhile, the standard treatment group’s goal was to achieve an HbA1c of between 7% and 7.9%, or close to the average HbA1c of people with diabetes in the United States. In reality, half the participants in this group achieved an HbA1c of less than 7.5%. Over the course of the study so far, both groups have lowered their average blood glucose levels compared to their levels before the study began.
The intensive treatment arm of the study has been stopped 18 months early, however, because more people in the intensive treatment group died compared to the standard treatment group. The difference was small—overall, 257 people in the intensive treatment group died and 203 people in the standard treatment group died, a difference of 54 total deaths or 3 deaths per 1,000 participants per year of the study. In both groups, the death rates were lower than had been seen in other studies of people with similar risk factors.
As the ACCORD trial continues, the researchers will seek an explanation for the difference in death rates between the groups. Analyses so far have not found a specific cause and have not implicated hypoglycemia or any blood-glucose-lowering drugs or combinations of drugs in the increase in deaths.
In light of the ACCORD trial’s findings, the American Diabetes Association (ADA) has released a statement advising people with diabetes who have cardiovascular disease or multiple risk factors for it to consult with their diabetes care team about their treatment goals and to make sure that their blood pressure and cholesterol levels are being properly controlled. However, the ADA also said that it “strongly encourages people with diabetes not to alter their course of treatment without first consulting their health care team” and that it “continues to encourage good control of blood glucose for the management of diabetes and its complications.” The statement went on to say that achieving an HbA1c level of less than 7% has been shown to reduce diabetes complications and “appears to be of great benefit rather than harm.”
The ADA currently recommends a general HbA1c goal of less than 7% for people with diabetes, but notes that treatment should be tailored to the individual. For some people it may be best to work toward an HbA1c level as close to normal as possible, while others—such as children, the elderly, and those with other medical conditions—may do best with less stringent goals. Some other groups, such as the American College of Endocrinology and the American Association of Clinical Endocrinologists, recommend an HbA1c target of 6.5% for people with diabetes.
Some of the media coverage of the ACCORD trial findings has been alarmist, but it is important to note that the trial is looking at a specific, high-risk group of people and that its findings may not be generalizable to all people with diabetes. In fact, another study published this week in The New England Journal of Medicine showed a reduction in overall death and cardiovascular death associated with intensive blood glucose control in a different high-risk population. The Steno-2 study, which followed 160 middle-aged people with Type 2 diabetes and microalbuminuria (kidney damage) found that people who underwent intensive therapy—with goals of an HbA1c of 6.5% or lower, cholesterol of 175 mg/dl, triglycerides of 150 mg/dl, and blood pressure of less than 130/80 mmHg—had a 20% reduction in risk of death and a 12.5% reduction in risk of cardiovascular death compared to those who received their usual treatment.
Previous trials, including the landmark United Kingdom Prospective Diabetes Study (UKPDS) of people with Type 2 diabetes and the Diabetes Control and Complications Trial (DCCT) of people with Type 1 diabetes have shown that intensive blood glucose control can substantially lower the risk of diabetes complications such as neuropathy, nephropathy, and retinopathy. (You can read more about both of these studies in the article “Managing Hyperglycemia.”). In addition, the Epidemiology of Diabetes Interventions and Complications Study (EDIC) study—a follow-up to the DCCT—found that intensive blood glucose control in people with Type 1 diabetes substantially reduced the long-term risk of developing cardiovascular disease.