The absolute risk reduction in major cardiovascular events due to antihypertensive therapy is broadly similar in people with and without type 2 diabetes, research shows.
The findings from a meta-analysis of major RCTs suggest differential blood pressure thresholds, intensities of blood pressure lowering, or drug classes are not warranted according to diabetes status.
The individual participant-level meta-analysis included data from 51 RCTs published between 1981 and 2014 involving 103,325 participants with type 2 diabetes and 255,208 participants without type 2 diabetes.
During 4.2 years of follow-up, 42,931 major cardiovascular disease events occurred — an incidence rate of 14.3 per 100,000 person-years of follow-up in participants with type 2 diabetes and 8.51 per 100,000 person-years of follow-up in participants without type 2 diabetes.
“A 5 mm Hg reduction in systolic blood pressure reduced the risk of developing a major cardiovascular event in participants with and in those without type 2 diabetes, with a weaker relative treatment effect in participants with type 2 diabetes (HR 0.94 [95% CI 0.91–0.98]) than in those without type 2 diabetes (0.89 [0·87–0.92]; pinteraction=0.0013),” the study authors said.
“The HRs for major cardiovascular events in participants with and without type 2 diabetes were proportional to the magnitude of the systolic blood pressure reduction obtained at the trial level, but to a lesser extent in people with type 2 diabetes versus those without.”
“Our findings showed that, although blood pressure-lowering treatment reduced the risk of major cardiovascular events in people with type 2 diabetes, the amount of the relative risk reduction was slightly smaller in those with type 2 diabetes than in those without type 2 diabetes, with no apparent treatment effect on ischaemic heart disease, cardiovascular-related death, and all-cause death.”
The study, published in The Lancet Diabetes & Endocrinology, said while the relative effects were weaker in participants with established type 2 diabetes than in those without, the higher risk of major cardiovascular events in people with diabetes meant the absolute risk reductions were broadly similar between the two groups.
The study showed no heterogeneity of effects by baseline categories of systolic blood pressure.
The authors, including Professor John Chalmers of the George Institute, Sydney, represent the Blood Pressure Lowering Treatment Trialists’ Collaboration. They said their findings challenge previous calls for adoption of blood pressure thresholds for use of antihypertensive therapy.
“Clinicians caring for people with type 2 diabetes should inform the individuals that antihypertensive therapy affords cardiovascular disease risk reduction that is proportional to the degree of blood pressure reduction and irrespective of their measured blood pressure.”
However they also noted that their findings “emphasise the importance of blood pressure lowering for cardioprotection before the onset of type 2 diabetes.”
An accompanying Comment article in the journal said the issue remained controversial.
“Interestingly, distinguished members of the European Society of Hypertension (ESH) recently published a review in which they identified a series of shortcomings of the previously published BPLTTC meta-analysis, allowing them to consider the conclusions of that meta-analysis as inadequate and that the suggestion made by the members of ESH to abandon the definition of hypertension should be rejected.”
The authors said more accurate measurement of blood pressure would help the debate as would taking into account the effects of SGLT2 inhibitors and finerenone on renal function and cardiovascular disease.