Blood pressure control is priority for Type 2 diabetics

May 19, 2003

New guidelines related to treatment of Type 2 diabetics with hypertension.

Management of blood glucose has been the traditional focus of diabetes care, but new guidelines from the American College of Physicians (ACP) suggest tight blood pressure control as equally important for Type 2 diabetics with hypertension. This conclusion followed a review of randomized, controlled trials measuring clinical outcomes in diabetics being treated for hypertension. Studies found that aggressive control of blood pressure led to a dramatic reduction in cardiovascular events and death and provided a possible benefit in preventing the microvascular complications of diabetes, such as retinopathy and nephropathy.

The focus has changed to include blood pressure control for two reasons, according to R. Keith Campbell, R.Ph., FASHP, certified diabetes educator (CDE) and associate dean/professor of pharmacotherapy at Washington State University College of Pharmacy. "The results of the United Kingdom Prospective Diabetes Study (UKPDS) showed that hypertension management is just as important as normalizing blood glucose in reducing diabetes complications," he explained. There is also emerging evidence that high blood pressure plays a role in the development of insulin resistance syndrome, a complex condition afflicting many diabetics.

Of the 16 million Americans with Type 2 diabetes, about 80% will develop or die from macrovascular complications, such as coronary artery disease, cerebrovascular disease, or peripheral vascular disease. With 11 million of these patients having coexisting hypertension, a major risk factor for developing these complications, researchers believe the importance of controlling blood pressure is clear.

The ACP guidelines recommend that clinicians aim for a target blood pressure of no more than 135/80 mmHg for their patients with diabetes. In the Hypertension Optimal Treatment (HOT) study, a four-point decrease in diastolic pressure from 85 to 81 mmHg led to a 50% decrease in risk for cardiovascular events. Although ACP determined the optimal systolic blood pressure has not been clearly defined in previous studies, the UKPDS results did show substantial decrease in mortality when levels were reduced from 154 mmHg to 144 mmHg. Authors of the guidelines suggest target systolic levels of 130 to 135 mmHg based on results from the Appropriate Blood Pressure Control in Diabetes (ABCD) trial, where the target systolic blood pressure in the two treatment groups of 138 mmHg and 132 mmHg resulted in mortality rates of 10.7% and 5.5%, respectively.

Another ACP objective was to determine whether any specific antihypertensive drugs were more effective or beneficial for patients with diabetes. They found thiazide diuretics and angiotensin-converting enzyme inhibitors (ACEIs) to be the best choices as first-line agents. Angiotensin-receptor blockers (ARBs) are considered an acceptable alternative if ACEIs are not tolerated.

"I would agree that thiazides or ACEIs should be used first," said Becky L. Armor, Pharm.D., CDE, assistant professor at University of Oklahoma College of Pharmacy. "Thiazides are cheap, work well in African-Americans, and have good evidence for stroke prevention—all important issues in diabetes management." Armor also noted that getting a diuretic on board early is useful for patients whose baseline blood pressure is more than 15 points above the American Diabetes Association (ADA) goal of 130/80 mmHg. "The benefits of ACEIs go beyond blood pressure lowering," she added, emphasizing their proven renal protective effect. "For diabetic patients who've already had a myocardial infarction (MI), stroke, congestive heart failure, or have begun to spill protein into their urine, the ACEIs are appropriate first-line options."

"I find the majority of patients require multiple agents to control their blood pressure to the targeted goal," said Magaly Rodriguez de Bittner, Pharm.D., BCPD, CDE, associate professor, University of Maryland School of Pharmacy and coordinator of the Giant Pharmacy Outpatient Diabetes Education Program. The combination of a diuretic and ACEI or ARB is powerful with synergistic effects, de Bittner added. "We must keep in mind the comorbidities of the patient and try to choose drugs that achieve target blood pressure control while being useful for other conditions." The guidelines also suggest that beta-blockers may be preferable for patients with known coronary artery disease, while calcium-channel blockers should be reserved as second- or third-line agents in patients with diabetes and avoided entirely by those who have had a recent coronary event.

The new guidelines were peer-reviewed by the ADA, the National Diabetes Education Program, and the American Academy of Family Physicians. A copy of the new guidelines can be found on the ACP Web site at http://www.acponline.org .

Heidi Belden, Pharm.D.

The author is a clinical writer based in Plymouth, Mass.