SAN FRANCISCO — Despite results from five major studies showing the effects of intensive glycemic control in patients with diabetes, the question remains: How low should one go?
Dr. Elizabeth J. Murphy distilled the data into a simple prescription for clinicians at a meeting on diabetes and endocrinology sponsored by the University of California, San Francisco.
For most patients with diabetes, aiming for a glycosylated hemoglobin (HbA1c) level below 7% “is still a very good goal,” said Dr. Murphy, chief of endocrinology at San Francisco General Hospital. Consider striving for lower HbA1c targets in younger, healthier, newly diagnosed patients “where you haven't seen adverse events. We know that in that population we can do the most to prevent the sequelae” of the disease, she added.
For patients who are expected to live less than 5 years or who have severe hypoglycemia, advanced complications, or other significant comorbid conditions, “higher targets like 8% might be appropriate,” Dr. Murphy said.
A 2009 position statement by the American Diabetes Association, American Heart Association, and American College of Cardiology reached similar conclusions in its interpretation of the recent data (Diabetes Care 2009;32:187-92). The position statement “is a long way of saying that we don't change anything,” Dr. Murphy said.
The new data and the joint position statement by the three groups were not enough to convince the American Association of Clinical Endocrinologists to modify its recommendation to aim for an HbA1c level below 6.5% in most patients, “but I still feel that less than 7%, given the data we have, is what we should stick with,” said Dr. Murphy, who based her advice on five key trials:
▸ 10-year follow-up of patients in the United Kingdom Prospective Diabetes Study (UKPDS) (N. Engl. J. Med. 2008;359:1577-89).
▸ Action to Control Cardiovascular Risk in Diabetes (ACCORD) study (N. Engl. J. Med. 2008;358:2545-59).
▸ Action in Diabetes and Vascular Disease: Preterax and Diamicron Modified Release Controlled Evaluation (ADVANCE) trial (N. Engl. J. Med. 2008;358:2560-72).
▸ Veterans Affairs Diabetes Trial (VADT) (N. Engl. J. Med. 2009;360:129-39).
▸ The Steno-2 trial from the Steno Diabetes Center in Copenhagen (N. Engl. J. Med. 2008;358:580-91).
All of the data, with the possible exception of VADT, suggest that lower HbA1c levels are better for preventing the microvascular complications of diabetes. To prevent macrovascular complications, the benefits of glycemic control are small in comparison to managing hypertension and dyslipidemia, which play far larger roles in morbidity and mortality.
“I hate to say this as an endocrinologist, but blood pressure control is much more important than glycemic control,” especially in patients with type 2 diabetes, she said, but “in type 1 diabetes that might not be the case.”
Aggressive treatment in the early stages of diabetes has long-lasting microvascular and macrovascular benefits, the data show, but aggressive blood pressure lowering must be continued to maintain the benefits.
Some of these major studies are ongoing, and “we will have to await longer follow-up” for a better picture of the relationship between HbA1c levels and cardiovascular complications, Dr. Murphy said.
She has been a consultant for Daiichi Sankyo Co., which markets drug therapies for diabetes.