Updated January 31, 2008

The Benefits of Tight Control
No End in Sight

by Wayne Clark

What does it mean to you?
The HbA1c test is considered the gold standard for the evaluation of blood glucose control. While the test has been in use for nearly 30 years, widely accepted target levels are a relatively recent development.

Before the DCCT, the American Diabetes Association’s (ADA) Standards of Medical Care (which is considered the primary source of recommendations for effective treatment), did not recommend a target HbA1c level. In response to the DCCT, the ADA in 1995 set a target of less than 7%, and set 8% as the “action” limit, above which additional intervention should be undertaken. The action limit was removed in the 2003 recommendations, effectively indicating that any level above 7% was cause for action.

The trend toward recommending lower blood glucose levels continued in 2004, when the ADA stated that “more stringent” targets could be considered for individuals. This year, that position was clarified further to indicate that while the HbA1c goal for people in general is less than 7%, the goal for an individual should be as close to normal (less than 6%) as possible without significant hypoglycemia.

“There’s no doubt, lower is better,” Dr. Spann says. “Is a 6% HbA1c achievable for every patient? Probably not. There are tradeoffs, such as the risk of hypoglycemia when striving for very tight control. The new ADA guidelines recognize that targets should be tailored to individuals.”

The ADA recommends that people meeting their treatment goals have an HbA1c test at least twice a year, and that those whose therapy has changed or who are not meeting their goals be tested four times a year.

It’s important not just to have the test, but to understand and be familiar with the results. A pair of recent studies found that only about a quarter of people with diabetes knew their most recent HbA1c value.

There is a growing recognition that the approach to diabetes management needs an overhaul to reflect the condition’s many challenges. An international task force called the Global Partnership for Effective Diabetes Management recently published a series of recommendations for Type 2 diabetes that includes aggressive interventions for any HbA1c level that stays above 6.5% for a six-month period. Combinations of oral diabetes drugs and the addition of insulin should be prescribed sooner, according to the group. Moreover, the group recommends pursuing cholesterol and blood pressure targets with equal aggressiveness, and implementing a multidisciplinary team approach to help people take control of their diabetes.

Meanwhile, the good news about tight blood glucose control keeps coming in. A DCCT/EDIC study published in December 2005 demonstrated that the risk of cardiovascular events was reduced by 42% in people who had been in the intensive treatment arm of the DCCT—even a dozen years after the study ended. The findings extended earlier observations that the intensive control group had slower progression of carotid intima–media thickness and coronary artery calcification, both signs of developing atherosclerosis (hardening of the arteries).

We will know in 2010 if the beneficial cardiovascular effect of intensive control extends to Type 2 diabetes. The Action to Control Cardiovascular Risk in Diabetes (ACCORD) trial is following 10,000 people with Type 2 diabetes across the United States and Canada for eight years, to determine the impact of intensive control (and also of cholesterol and blood pressure treatment) on the development of cardiovascular disease.

“The bottom line is that this is very difficult,” Dr. Spann says. “As our study and others have shown, even with good practices with good physicians, and even with motivated patients, it’s so hard that only 40% of people hit the targets. But there’s really solid evidence that hitting those targets prevents blindness, amputations, and kidney disease. That’s a significant payoff—and a reason to keep trying.”

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