How Low Should Blood Pressure Go in Diabetes Patients?

High blood pressure is an established risk factor for cardiovascular events in patients with diabetes.

Nevertheless, lowering blood pressure in diabetics is an area for debate, given the current controversy surrounding which patients should be prescribed blood pressure-lowering treatment and what blood pressure targets should be set for them.

Although current major hypertension guidelines have established less-aggressive target levels for blood pressure lowering in diabetics than previous recommendations, subsequent research published in JAMA found that that a more-aggressive blood pressure target <130 mm Hg is associated with a lower risk of stroke, retinopathy, and albuminuria.

In fact, the study authors determined that each 10-mm Hg lower systolic blood pressure was associated with a lower risk of mortality, cardiovascular disease events, coronary heart disease events, stroke, albuminuria, and retinopathy in patients with type 2 diabetes, which they wrote “support the use of medications for [blood pressure] lowering in these patients.”

Before arriving at these conclusions, the researchers conducted a systematic review and meta-analysis of 40 randomized, controlled, blood pressure-lowering trials involving 100,354 patients. Using these data, they examined the associations between blood pressure-lowering treatment and vascular disease in type 2 diabetes.

After stratifying the trials by mean initial systolic blood pressure level (≥140 mm Hg to <140 mm Hg), the researchers found that a 10-mm Hg systolic blood pressure lowering was significantly associated with lower relative risks for mortality, CVD events, coronary heart disease events, and heart failure among those with mean baseline systolic blood pressure of ≥140 mm Hg. In addition, blood pressure-lowering treatment was associated with lower risks of stroke and albuminuria, regardless of initial systolic blood pressure.

Similarly significant associations were seen between 10-mm Hg systolic blood pressure lowering treatment and outcomes stratified by achieved systolic blood pressure, as there were lower relative risks for mortality, CVD events, coronary heart disease events, heart failure, and albuminuria in the ≥130 mm Hg stratum than the stratum <130 mm Hg.

Overall, few differences were observed between medication classes in terms of the associations between blood pressure-lowering treatment and outcomes.

“These findings are timely, clear, and important and lend support to current guideline recommendations to consider offering patients with type 2 diabetes antihypertensive therapy when their systolic BP is 140 mm Hg or greater, aiming for a target systolic [blood pressure] toward 130 mm Hg, but not usually lower than this,” Bryan Williams, MD, of University College London, wrote in an accompanying editorial.

For some patients, Dr. Williams continued, this blood pressure threshold and target may still be too conservative for optimally reducing the risk of stroke and the onset or progression of albuminaria, in particular.

“This conundrum highlights the problems with clinician overreliance on guidelines and guideline overdependence on an often-uncritical adoption of evidence, despite the limitations of the clinical trials,” Dr. Williams wrote. “Guidelines are just that, and are necessarily conservative in providing population-based recommendations that physicians must interpret in the context of the individual patient being treated.”