High BP and HbA1c: Similar Risks for CVD in Youth With Type 1 Diabetes

Becky McCall

June 13, 2019

SAN FRANCISCO — Controlling blood pressure is as important as keeping glucose in check when it comes to the prevention of cardiovascular (CV) events in young people with type 1 diabetes, say US researchers, who found that CV risk doubles if blood pressure levels hit 120/80 mmHg or higher.

"We see that the high blood pressure group and the high HbA1c group present a similar risk for heart disease in this high-risk population," said Jingchuan Guo, MD, PhD, a postdoctoral fellow from the Center for Pharmaceutical Policy and Prescribing (CP3) at the University of Pittsburgh, Pennsylvania, who presented the data here at the American Diabetes Association (ADA) 2019 Scientific Sessions.

"Our study suggests that in type 1 diabetes optimal blood pressure goals may be lower — for example, 120/80 mmHg — than currently recommended," she added during a press conference to discuss the findings, which were also reported in a poster here.

This is the first study to generate robust data on the issue, which was recently highlighted by the ADA in their Standards of Medical Care, 2019. In this document, the organization notes the "absence of high-quality data to guide blood pressure targets in type 1 diabetes."

Existing recommended blood pressure targets for patients with type 1 and type 2 diabetes are 140/90 mmHg for those with a 10-year cardiovascular disease (CVD) risk < 15%, or 130/80 mmHg for people with existing CVD or 10-year CVD risk > 15%.

Trevor Orchard, MD, also of the University of Pittsburgh and senior investigator of the new analysis, pointed out that "at the moment [the target for] children [with type 1 diabetes] will be...120/80 mmHg, and then when they turn 21 years of age, that goal becomes 140/90 mmHg. This is ridiculously nonrepresentative of the risk for this population."

He added that another reason why the guidelines have not been rigorously addressed for type 1 diabetes is the lack of clinical trial data, reflecting the fact that type 1 diabetes is a relatively minor part of the whole diabetes picture.

"Trials with CV outcomes in 3000 to 5000 people are not appealing enough to the pharmaceutical industry. We are at the point where we need to address this based on observational data, not just ours but maybe from...other studies. We can't go on saying we have no evidence now," he said.

Young T1D Patients at High CVD Risk, Clarity Needed on BP Targets

CVD is a leading cause of death in type 1 diabetes, and the risk is particularly high for younger patients, said Guo.

"CVD occurs around 10 to 15 years earlier in this population, and young adults with type 1 diabetes have recently been shown in three studies to be 20 to 30 times more likely to die from heart disease than young people without the disease," she stressed to assembled reporters.

The current analysis followed youth with child-onset type 1 diabetes without known baseline coronary artery disease (CAD) for 25 years and aimed to determine optimal blood pressure goals for minimizing CAD risk, and to compare blood pressure and glucose levels in terms of predicting CAD.

The analysis was based on 605 participants from the Pittsburgh Epidemiology of Diabetes Complications (EDC) study, which enrolled patients with type 1 diabetes diagnosed at age 17 years or younger and who were seen within 1-year of diagnosis at the Children's Hospital of Pittsburgh in 1986-1988. Mean age was 27 years and average duration of type 1 diabetes was 19 years.

Participants' blood pressure was measured at years 2, 4, 6, 8, 10, 18, and 25, and mean arterial pressure was also calculated. Time-weighted blood pressures were determined to reflect long-term blood pressure exposure, and optimal blood pressure cut-offs for best predicted risk were estimated. These were determined to be 120 mmHg for systolic blood pressure and 80 mmHg for diastolic blood pressure.

Risk was then further stratified according to four groups: those with good control of both blood pressure and HbA1c (reference group); those with high blood pressure only (≥ 120/80 mmHg) but good glycemic control; those with high HbA1c (≥ 8%) but good blood pressure control; and finally poor control of both blood pressure (≥ 120/80 mmHg) and HbA1c (≥ 8%). 

Compared with patients in the reference group, the high blood pressure only group had double the risk of CVD (hazard ratio [HR], 2.0), and in fact, had a similar risk as the high HbA1c only group (HR, 1.7).

For those with both high blood pressure and high HbA1c, the risk was even higher, and in fact, was triple (HR, 3.1).

Reflecting on the results, Guo asserted that "Young adults with type 1 diabetes should have careful monitoring of their blood pressure. Because of the absence of randomized controlled trial data [on this topic], our findings should be considered."

"Since blood pressure control is likely to be as important as glucose control for CV risk prevention in people with type 1 diabetes, the initial treatment focus should be on glucose control, when HbA1c is very high, but as HbA1c approaches the high-normal range, an increasing focus on blood pressure becomes critical," she observed.

Moderator of the press briefing, Desmond Schatz, MD, medical director of the University of Florida Diabetes Institute, Gainesville, told journalists: "I think the next step in this discussion around blood pressure thresholds is knowing which guidelines should be followed for children with type 1 diabetes."

"We want to know what the right blood pressures are that we should aim for more aggressively to prevent these adverse outcomes happening."

Guo has reported no relevant financial relationships. Orchard has reported being a consultant for Boehringer Ingelheim

ADA 2019. Presented June 8, 2019. Abstract 1464

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