The team from Omaha’s Veterans’ Affairs Medical Center said that, although evidence supports upper BP treatment thresholds, there is little evidence on how far BP should be lowered.
The researchers studied 1,791 patients with type-2 diabetes and hypertension.
Their results supported treatment of patients with systolic BP about 140mmHg and a diastolic BP below 80mmHg.
But they also found that patients with a diastolic BP below 70mmHg were more than twice as likely as those with higher diastolic BP to suffer a cardiovascular event. This risk increased at even lower diastolic BPs - those with diastolic BPs below 60mmHg were 2.8 times more likely to suffer a cardiovascular event.
The researchers commented: ‘The results supported the conclusion that a diastolic BP of <70 mmHg is the level at which CVD risk begins to increase significantly, with further enhanced significant risks with diastolic BP <60 mmHg.’
They added: ‘A possible negative effect of antihypertensive treatments that excessively lower DBP must be considered.’
The researchers said that future studies should look at whether BP control changed outcomes for individual patients in higher risk systolic of diastolic BP categories.