Blood Pressure–Lowering Treatment for the Prevention of Major CVDs in People With and Without Type 2 Diabetes
The Lancet Diabetes & Endocrinology.11th July
1 Expert Comment

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This meta-analysis of 51 major randomised controlled trials between 1981 and 2014 involving 358,533 participants investigated the effects of blood pressure lowering on the risk of major cardiovascular events by type 2 diabetes status. A 5–mm Hg reduction in systolic blood pressure decreased the risk of major cardiovascular events in both groups, with a weaker treatment effect in patients with type 2 diabetes. There was no difference in absolute risk reductions between the two groups.

Given that there are no absolute differences in the risk of major cardiovascular events between people with type 2 diabetes and those without type 2 diabetes, differential blood pressure thresholds and intensity of blood pressure lowering may not be warranted in patients with type 2 diabetes compared with patients without type 2 diabetes.

Discussion
Do the effects of blood pressure–lowering treatment on the risk of major cardiovascular events differ between people living with and without type 2 diabetes? And should a specific blood pressure threshold to initiate blood pressure–lowering treatment differ between people with and without type 2 diabetes? To address these questions, Nazarzadeh et al conducted an individual participant-level data meta-analysis of major randomised controlled trials using the Blood Pressure Lowering Treatment Trialists’ Collaboration dataset (BPLTTC). They analysed data on 51 randomised clinical trials, involving 103,325 individuals with type 2 diabetes and 255,208 individuals without type 2 diabetes.

In both individuals with and without type 2 diabetes, a 5-mmHg reduction in systolic blood pressure reduced the risk of developing a major cardiovascular event. A weaker relative treatment effect was noted for individuals with type 2 diabetes (HR, 0.94; 95% CI: 0.91-0.98) than for those without (HR, 0.89; 95% CI: 0.87-0.92). This heterogeneous treatment effect was mostly driven by ischaemic heart disease, but was similarly observed for cardiovascular death and all-cause death. It was reported that the group differences in relative treatment effects between individuals with and without diabetes were not related to levels of systolic blood pressure at baseline or type of blood pressure–lowering therapy used. In contrast, the absolute risk reduction was similar between individuals with and without type 2 diabetes, mostly due to a higher baseline risk of major cardiovascular events in individuals with type 2 diabetes.

The results of the meta-analysis have a major implication for clinical practice, as these indicate that there is no need to apply differential blood pressure thresholds, intensities of drug classes or allocate different drug classes when controlling hypertension in people with and without type 2 diabetes. However, these findings may or may not apply to populations often not eligible for inclusion in intensive blood pressure treatment trials, such as older adults with multimorbidity.1 It is also unclear whether the findings would apply to patients utilising some of the newer classes of therapies such as GLP-1 receptor agonists and SLGT2 inhibitors with proven cardiovascular benefits beyond any effects on blood pressure lowering.

G Mohan

This evidence strengthens recommendations for similar blood pressure thresholds, intensities of drug classes, and allocation of drug classes for the majority of individuals with and without 2 diabetes, but does not negate the need for incorporating risk stratification in the practice workflow to optimise decision making and patient blood pressure control.