The 2008 American Heart Association Meeting

The 2008 American Heart Association meeting is a huge conference withover 26,000 attendees. This year we found ourselves in historic New Orleans where fantastic music, food, and street performers are never far away.

A lot of the discussion related to diabetes at this meeting was focused on identifying and quantifying the link between diabetes and its impact on the risk for heart disease.

This issue of Conference Pearls delves into the debate about whether or not enough research has been done to say for sure that intensive diabetes treatment reduces the risk of heart disease. A lot of this debate has been caused by conflicting results from recent trials such as ACCORD, ADVANCE, VADT and older studies such as UKPDS, and DCCT/EDIC.

We have included some background on these important studies below. For a more detailed look, visit diatribe.us/issues/9/what-were-reading, diatribe.us/issues/12/conference-pearls, and diabetes.niddk.nih.gov/dm/pubs/control.

research background

• In summary, the 10,000-subject ACCORD study was designed to see how intensive blood glucose control affected the rates of heart disease and stroke in patients with type 2 diabetes at high risk for these complications. The intensive group in the study targeted A1c levels under 6% and the less intensive group targeted A1c between 7.0% and 7.9%. Last February, the intensive arm of the trial was halted by the Data Safety Monitoring Board (an independent group that ensures the safety of clinical trials) due to an unexpected increased risk of death associated with intensive diabetes treatment in this arm. ACCORD also didn’t show any improvement of cardiovascular risk with intensive management. 

• The ADVANCE trial is the largest clinical trial ever conducted on diabetes, with over 11,000 patients studied. This trial continues to look at the intensive management of patients with type 2 diabetes who are at high risk for cardiovascular disease. Early results did not show the unexpected increased risk of death seen in ACCORD. 

• The UKPDS trial was done in the 1980s to examine the long-term effects of blood sugar and blood pressure control on type 2 diabetes. Participants in the UKPDS trial were tracked for 10 years after the trial ended as part of the UKPDS follow-up study. In this follow-up, researchers found that people who had been in the intensive glucose control group - meaning that they had achieved good control of their blood sugars in the past (for a median of 11 years) - still had a benefit in terms of microvascular and some macrovascular complications even 10 years later! Some researchers have described this as a “legacy” effect.

• The DCCT and EDIC studies were done in the 1980s and 1990s respectively on patients with type 1 diabetes. The DCCT looked at the effect of good glucose control on microvascular disease (eye, kidney, nerve damage) while EDIC, the follow-up study to DCCT, looked at the effect on macrovascular disease (heart disease and stroke). These studies also showed a similar “legacy” effect of good early control on preventing microvascular and macrovascular disease in type 1s.

is intensive treatment of diabetes a good way to reduce the risk of heart disease?

Most of the speakers at the AHA conference who addressed this question called for more studies to prove beyond a doubt that intensively treating diabetes is effective in reducing the risk of heart disease.

Dr. David Goff from the Wake Forest University School of Medicine believes we need more studies to answer this question and provide evidence for best medical practices. This was based strongly on the findings from the ACCORD, ADVANCE and the UKPDS studies. These studies suggest rapidly lowering average blood glucose in certain patients does not reduce the risk of cardiovascular events such as heart attacks, at least in the short term. He speculated that for certain patients it does not make sense to try and decrease average glucose levels too quickly. He also pointed out the need to carefully examine the types of patients taking part in these trials when using these results to define best practices. Pointing to the “legacy” effect from the UKPDS 10-year follow-up results, he suggested that surviving participants in the intensively controlled arm of the ACCORD study might yet see some macrovascular benefit much later on. He concluded that our current course of action should be to control all known cardiovascular disease risk factors like blood pressure, cholesterol, triglycerides, and weight.

Dr. Theodore Mazzone of the University of Illinois also concluded that we do not yet have sufficient evidence to widely recommend prevention of diabetes as a treatment for cardiovascular disease. Likewise, Dr. Naveed Sattar of the University of Glasgow (Scotland, UK) proposed instead that the risk of developing diabetes depends on body mass index (BMI), triglyceride levels, glucose and insulin resistance, while prevention of coronary heart disease should emphasize controlling LDL cholesterol levels, blood pressure, and smoking.

In short, there does not appear to be enough evidence to say that all people with diabetes should be on intensive glucose control therapy in order to reduce heart disease. It’s going to take a very long, carefully designed, and expensive clinical study to prove this for macrovascular disease. For people with diabetes who have already had heart disease, it is particularly important that you and your healthcare team discuss your heart disease and diabetes management priorities.

Remember, however, that intensive control has already been proven to prevent future microvascular disease. Also, remember that the ADA still recommends targeting an A1c of goal of under 7% for non-pregnant adults with diabetes for both microvascular and macrovascular disease risk reduction. These discussions of ‘intensive’ therapy are talking about going BELOW 7%, and won’t impact your blood glucose targets until the dilemma is resolved.