Stricter BP thresholds may be needed in type 1 diabetes
medwireNews: Findings from an observational cohort study suggest that a blood pressure (BP) target of 120/80 mmHg may be needed for effective prevention of coronary artery disease in people with type 1 diabetes.
Having BP above this threshold was associated with a similar risk level as having glycated hemoglobin (HbA1c) levels above 8% (64 mmol/mol), researcher Jingchuan Guo (University of Pittsburgh, Pennsylvania, USA) told journalists at the 79th ADA Scientific Sessions in San Francisco, California, USA.
The data came from 605 participants of the Pittsburgh Epidemiology of Diabetes Complications Study of Childhood-onset Type 1 Diabetes, who were followed up for an average of 25 years, so the BP and HbA1c measures were cumulative and time-weighted. The participants were an average age of 27 years at baseline, with an average diabetes duration of 19 years.
The researchers looked at BP cutoffs ranging from 110 to 140 mmHg systolic and from 60 to 90 mmHg diastolic. They found 120/80 mmHg to be the optimal cutoff; people with BP above this threshold had a 2.0-fold increased risk for incident coronary artery disease during follow-up.
Guo emphasized that the ADA Standards of Care currently advise a BP target of 140/90 mmHg for most people with diabetes, and 130/80 mmHg for those with existing cardiovascular disease or with a 10-year risk exceeding 15%.
But the recommendations also note the current lack of high-quality evidence for specific BP targets in people with type 1 diabetes. Guo said that “because of the absence of direct randomized clinical trial data, our findings should be carefully considered in clinical settings.”
The risk increase with above-threshold BP was similar to that found for HbA1c above 8%, which increased coronary artery disease risk 1.7-fold. The two risk factors combined were associated with a 3.1-fold increase in risk.
Commenting on BP targets in the guidelines, co-researcher Trevor Orchard, also from the University of Pittsburgh, highlighted the “absurd situation here now that children will be at [a BP target of] 120/80 and then they become 21 years old and suddenly that goal is up to 140/90, which is ridiculously non-representative of the risk change.”
He attributed the paucity of clinical trial data to the fact that BP is “a relatively minor” contributor to outcomes in type 1 diabetes, meaning that cardiovascular outcome trials would need to be very large, and so not appealing to pharmaceutical sponsors.
Orchard therefore stressed the need to start basing BP threshold guidance on observational studies, arguing that the lack of clinical trial data can no longer be used as a reason for inaction. “We have to take the pill and swallow it,” he said.
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