In the past few years, there has been vigorous debate about how low blood pressure targets should be for people with diabetes. This debate has been informed by studies that often give conflicting or unclear impressions of the risks and benefits of different blood pressure targets. For example, a couple of years ago, we wrote about a study that found a lower risk of stroke and heart attack — but a higher risk of overall death — in people with Type 2 diabetes who achieved the lowest blood pressure targets.
The American Diabetes Association currently recommends setting a treatment goal of below 140 for most people with diabetes, but notes that a goal of below 130 may be appropriate for some people — and many doctors prefer to aim for this lower number. (Normal systolic blood pressure is generally considered below 120.) Some studies, though, question the wisdom of aiming for lower targets — while others lend support to this practice.
Two recent studies show how difficult it can be to know what blood pressure targets to aim for in people with diabetes.
Different studies, different results
One of the studies, published in December 2017 in the journal Diabetes Care, looked at participants in a study known as ACCORD-BP (Action to Control Cardiovascular Risk in Diabetes Blood Pressure). Only those aiming for standard blood glucose control, and who also had certain cardiovascular disease risk factors, were eligible for the analysis.
Within this group, participants who underwent intensive blood pressure control — achieving an average systolic blood pressure of 120 mmHg — had a slightly lower risk of cardiovascular disease than those who underwent standard blood pressure control, who achieved an average systolic blood pressure of 134 mmHg.
The combined risk of death from cardiovascular causes, nonfatal heart attack, nonfatal stroke, heart failure, and undergoing procedures to restore or improve blood flow was 21 percent lower in the intensive control group than in the standard blood pressure control group. There was no difference in these results between people with and without diabetes
In the other study, published in March 2018 in Diabetes Care, researchers looked at the results of achieving various blood pressure targets in people with Type 2 diabetes who started taking a new drug to more aggressively treat their high blood pressure.
Over a follow-up period lasting about 5 years on average, participants who achieved a systolic blood pressure of less than 120 mmHg were more likely to have cardiovascular disease (CVD) than those who only achieved a level below 130 or 140 mmHg. In fact, these participants were 75 percent more likely to have CVD than members of the below-130 group, and 67 percent more likely to have CVD than those in the below-140 group.
What’s the lesson?
It’s hard to know what lesson to draw from these two studies, since their results seem to contradict one another.
It’s worth noting that neither study was a randomized controlled trial, which means that participants weren’t randomly selected to achieve certain blood pressure goals. This means that differences in participants’ underlying health might have affected both their blood pressure results and their risk for CVD — which means you should take both studies with a grain of salt.
It’s also worth noting a difference between the two studies that may or may not be important. The December 2017 study simply looked at what level of systolic blood pressure participants achieved, while the March 2018 study looked at the results of adding an additional treatment when participants’ initial treatment wasn’t adequate. It’s possible that in the first study, participants who achieved lower blood pressure were simply those who responded better to treatment, while the second study included people whose blood pressure was hard to treat. These differences might affect CVD risk.
In the end, you can’t know whether you, as an individual, will have a higher or lower risk of CVD based on exactly how much you lower your blood pressure. Each study includes a range of outcomes among individuals, and it’s up to researchers to make sense of the results — which will eventually inform guidelines about how patients should be treated.
What’s your take on these studies, and on the larger controversy over blood pressure targets in people with diabetes? Are you worried that your blood pressure might be under- or overtreated? Has your doctor changed your blood pressure target in response to changing guidelines, or your changing health? Leave a comment below!
Want to learn more about diabetes and blood pressure? Read “Seven Little-Known Steps for Lowering Your Blood Pressure,” “The Pressure Is On: Hypertension and Diabetes,” and “When Is Blood Pressure Too Low.”