Rethinking Lower Blood Pressure Goals for Diabetic Patients with Coronary Artery Disease.

Tight control of high blood pressure, recommended for those with diabetes by national guidelines, gives no better results than moderate control, according to a new study conducted by Rhonda M. Cooper-DeHoff of the University of Florida and her colleagues. The study is published in the Journal of the American Medical Association.
 
Hypertension guidelines advocate treating systolic blood pressure (BP) to less than 130 mm Hg for patients with diabetes mellitus; however, data are lacking for the growing populations who also have coronary artery disease.
 
For this study, Cooper-DeHoff and colleagues looked at a subgroup of 6400 participants of a large study, called INVEST (International Verapamil SR-Trandolapril Study). It included more than 22000 participants from 14 countries who were at least 50 years old and had high blood pressure and coronary artery disease. Study participants enrolled in the study from 1997 to 2000 and were followed through March 2003, with follow-up for US participants extended through August 2008.
  
INVEST compared two blood pressure lowering approaches, with participants given either a calcium antagonist medication first or a beta-blocker medication, followed by more drugs if needed to lower pressure. Next, the researchers categorized the 6400 participants into three groups:
-   35.2% had tight control with systolic pressure maintained at below 130mmHg
-   30.8% had moderate or usual control with pressures from 130mmHg to under 140mmHg
-   34% had uncontrolled with pressures above 140mmHg
 
During the follow-up, researchers looked to see which of the groups categorized by the amount of control were more likely to die from any cause or to have a heart attack or a stroke. Little difference was found between the tight control and moderate control groups.
The primary outcome occurred in 12.7 percent of those in the tight-control group, 12.6 percent of the usual-control group, and 19.8 percent of the uncontrolled groups. When evaluating all-cause mortality for the entire follow-up period, after adjustment, risk of all-cause mortality was significantly greater in the tight-control group (22.8 percent) than in the usual-control group (21.8 percent).
 
"The guidelines suggest you want diabetics to have systolic pressure under 130mmHg,"says researcher Cooper-DeHoff. But in her study, those who kept their systolic pressures moderately controlled - at 130mmHg to 139mmHg - did as well as those who controlled it more tightly. There was no difference comparing those with tight control or usual control which is contrary to what the guidelines would suggest.
 
"The message is: we need to get diabetic patients' systolic blood pressure to less than 140mmHg, particularly when they have heart disease, but working to get it to less than 130mmHg does not appear to add any additional benefit with regard to the risk of death, stroke, or heart attack." Copper-DeHoff said.
 
She warned that even through the guidelines recommending lower blood pressures in those with diabetes have been in place for nearly 20 years, there is a paucity of evidence supporting this recommendation, particularly for lower systolic blood pressure.
 
P.K. Shah, a cardiologist of the Sinai Medical Center said the moderate blood pressure control was a reasonable range to shoot for which means moderate control of blood pressure is effective. But drug- induced lowering of blood pressure is not the same as natural low blood pressure for blood pressure lowering by drugs does not mimic all the good effects of having naturally low pressure.