US study findings suggest that low diastolic blood pressure (BP) readings may place patients with Type 2 diabetes at increased risk for cardiovascular disease (CVD) events.

The study authors found that while elevated systolic BP was associated with an increased risk for CVD events, a diastolic BP of less than 70 mmHg also increased this risk, even if accompanied by a systolic BP within guideline-recommended target ranges.

“Our results underscore a dilemma for physicians who identify Type 2 diabetes patients with mild increases in systolic BP (eg, 130-139 mmHg or 140-145 mmHg) and diastolic BP 60-69 mmHg or lower,” say Robert Anderson (Veterans Affairs Medical Center, Omaha Nebraska) and colleagues.

“Should they treat the systolic BP aggressively with attendant lowering of diastolic BP, the consequence could be a shift of the patient into a higher CVD risk category.”

The findings come from the Veterans Affairs Diabetes trial, a prospective study comparing intensive versus standard glucose treatment for up to 7 years in 1791 patients with a substandard response to maximum oral agents or insulin.

Those with hypertension (n=1289; defined as current treatment for hypertension or a BP of 140/90 mmHg or greater) received stepped treatment to maintain BP below 130/80 mmHg.

All patients were followed for the primary outcome of a first occurrence of myocardial infarction, stroke, congestive heart failure, surgery for vascular disease, inoperable coronary disease, amputation for ischemic gangrene, or CVD death.

As an individual component, systolic BP of at least 140 mmHg was associated with a significant risk for this outcome, both at baseline and on-study (hazard ratio [HR] =1.51 and 1.47, respectively).

Diastolic BP less than 70 mmHg was also significantly associated with these events at baseline and on-study (HR=1.48 and 1.49).

Combining BP categories showed that systolic readings of at least 140 mmHg with diastolic BP less than 70 mmHg at baseline and on-study were associated with the primary outcome (HR=1.79 and 2.04). The same was true for nearly all systolic readings with a diastolic BP of less than 70 mmHg.

Reporting in the journal Diabetes Care, the researchers say: “Our results support the identification of a new category of high CVD event risk for the group of Type 2 diabetes patients with low diastolic BP.”

MedWire (www.medwire-news.md) is an independent clinical news service provided by Current Medicine Group, a trading division of Springer Healthcare Limited. © Springer Healthcare Ltd; 2010

Free abstract

Intensive blood pressure (BP) control does not reduce the rate of cardiovascular (CV) events in patients with Type 2 diabetes and high CV risk, reveals research presented at the 59th Annual Scientific Sessions of the American College of Cardiology in Atlanta, Georgia, USA.

The Action to Control Cardiovascular Risk in Diabetes (ACCORD) Blood Pressure trial found that targeting therapy in such patients to achieve a systolic blood pressure (SBP) below 120 mmHg did not significantly reduce the annual rate of a composite of nonfatal myocardial infarction, nonfatal stroke, or death from CV causes, compared with a standard blood pressure target of below 140 mmHg.

A total of 4733 patients aged an average of 62.2 years with Type 2 diabetes were randomly assigned to intensive BP control (n=2362) or standard BP control (n=2371). The patients had an average baseline SBP of 139 mmHg, ranging from 130 to 180 mmHg, and had stable diabetes for at least 3 months, with a HbA1c of 7.5% to 11.0%. Also, 33.7% of patients had CV disease (CVD), while the remainder had subclinical CVD or at least two risk factors.

Patients in the intensive group were initiated on a two-drug therapy, typically a thiazide-type diuretic plus ACE inhibitor, angiotensin receptor blocker, or beta blocker. Drugs were then added and/or titrated at monthly visits to achieve the target SBP of 120 mmHg. In the standard group, therapy was intensified if SBP was 160 mmHg or above at the first visit or 140 mmHg or above at the second visit.

William Cushman, from the Veterans Affairs Medical Center in Memphis, Tennessee, USA, noted that “the SBP separated very early.”

He reported that BP from a year onward averaged at about 134 mmHg for the standard therapy group and at about 119 mmHg for the intensive therapy group.

This meant that, on average, a delta difference in BP of 14 mmHg was achieved from 1 year to the end of the 4.7-year study, which Cushman said was “certainly far greater” than the 10 mmHg minimum that they had set out to achieve.

Patients in the intensive treatment group took more drugs over the course of the study than did those in the standard treatment group, at an average number of 3.4 versus 2.1. Despite the difference in SBP, the patients receiving intensive BP-lowering therapy had a similar risk for the primary outcome as patients receiving standard therapy, at rates of 1.87% and 2.09%, respectively, and a hazard ratio of 0.88 (p=0.20).

The findings, published simultaneously advance online by the New England Journal of Medicine, did show about a 40% reduction in the risk for stroke in the intensive therapy group compared with the standard therapy group, however. And although this finding is consistent with meta-analyses summarizing the impact of a 10-mmHg reduction in SBP on stroke in observational studies, Cushman pointed out that the overall rate of stroke was very low, at about 0.5% per year.

“Therefore, although intensive management did significantly reduce total stroke and nonfatal stroke, assuming that this finding is real… the number needed to treat to lower the SBP to prevent one stroke over 5 years was 89.”

Cushman cautioned that patients receiving intensive therapy were also at increased risk for complications attributed to antihypertensive treatment compared with those receiving standard therapy, with occurrences seen in 3.3% versus 1.3% of patients. But overall serious adverse events were of a low order.

He concluded: “The results find no conclusive evidence that the intensive BP control strategy reduces the rate of a composite of major CV events, which was all-cause or fatal CV events plus nonfatal myocardial infarction and nonfatal stroke in high-risk adults with Type 2 diabetes.”

MedWire (www.medwire-news.md) is an independent clinical news service provided by Current Medicine Group, a trading division of Springer Healthcare Limited. © Springer Healthcare Ltd; 2010

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