NEW YORK (Reuters Health) – Elevated systolic blood pressure and low diastolic blood pressure are associated with increased risk of cardiovascular disease (CVD) among patients with type 2 diabetes, according to results from the Veterans Affairs Diabetes Trial (VADT) published online in the November 8th Diabetes Care.

Systolic blood pressures of 140 mmHg and higher and diastolic blood pressure below 70 mmHg at baseline and during follow-up were associated with a significantly increased risk of cardiovascular disease. The diastolic risk existed regardless of the associated systolic blood pressure.

Current evidence supports maintaining systolic blood pressure below 140 mmHg, and both the American Diabetes Association and the JNC-7 blood pressure guidelines recommend maintaining blood pressure below 130/80 mmHg in patients with diabetes. It remains unclear, though, how low the blood pressure can safely be reduced and whether low blood pressure contributes to CVD risk.

To address these issues, Dr. Robert J. Anderson from the VA Medical Center, Omaha, Nebraska, and colleagues used data from 1791 VADT participants with hypertension to determine whether baseline and follow-up systolic and/or diastolic blood pressure predict CVD events.

When patients were grouped according to diastolic blood pressure, it became clear that a diastolic blood pressure of 70 mmHg is the level at which CVD risk begins to increase significantly, and the risk is further enhanced when diastolic blood pressures fall below 60 mmHg.

Blood pressure in the prehypertensive range (120-139 mmHg systolic, 80-89 mmHg diastolic), however, wasn’t associated with significant increases in CVD risk in this population.

“Our results support the identification of a new category of high cardiovascular disease event risk for the group of type 2 diabetes patients with low diastolic blood pressure,” the investigators note.

Whether measures taken to alter blood pressure could influence CVD risk in this population remains unclear. “We did not look at the effects of lowering blood pressure in patients in this analysis,” the researchers explain. “A possible negative effect of antihypertensive treatments that excessively lower diastolic blood pressure must be considered.”

“Future research questions include whether blood pressure control changed outcomes for individual patients in higher risk systolic blood pressure or diastolic blood pressure categories,” they add. “We also plan to investigate the potential associations of these high risk blood pressure categories with microvascular events.”

In the meantime, the authors emphasize “the urgency for treatment of systolic hypertension” and suggest that diastolic blood pressures below 70 mmHg in these patients “may best be avoided.”

Reference:

BLOOD PRESSURE AND CARDIOVASCULAR DISEASE RISK IN THE VETERANS AFFAIRS DIABETES TRIAL (VADT)


Diabetes Care 2010.