medwireNews: Reducing blood pressure (BP) may be an effective strategy for the prevention of new-onset type 2 diabetes, suggest researchers from the Blood Pressure Lowering Treatment Trialists’ Collaboration.
They note, however, that different classes of BP lowering drugs “have qualitatively and quantitively different effects on diabetes, likely due to their differing off-target effects, with angiotensin-converting enzyme inhibitors and angiotensin II receptor blockers having the most favourable outcomes.”
The findings are based on a meta-analysis of individual data for 145,939 participants (60.6% men) from 19 randomized controlled trials of antihypertensives.
During a median 4.5 years of follow-up, 9883 participants were diagnosed with new-onset type 2 diabetes, at incidence rates of 15.94 per 1000 person–years in the BP lowering drug intervention group and 16.44 per 1000 person–years in the comparator group (placebo or another antihypertensive).
Kazem Rahimi (University of Oxford, UK) and co-investigators calculated that a 5 mmHg reduction in systolic blood pressure during BP lowering treatment was associated with an 11% reduction in the risk for diabetes versus comparator treatment across all trials.
They then conducted a network meta-analysis of 22 trials to investigate the individual effect of each BP lowering drug class.
This revealed that use of an angiotensin-converting enzyme inhibitor or angiotensin II receptor blocker was each associated with a significant 16% reduction in diabetes risk versus placebo.
Calcium channel blockers had no significant impact on diabetes risk but the use of beta blockers and thiazide diuretics was associated with significant 1.48- and 1.20-fold increased risks for diabetes versus placebo, respectively.
“This adverse diabetes effect supports recommendations to classify these agents as low priority for treating hypertension when the risk of diabetes or prediabetes is of clinical concern,” write Rahimi and co-authors in The Lancet.
The researchers confirmed their findings in a mendelian randomization analysis, which showed that each 5 mmHg decrease in genetically influenced lower systolic blood pressure was associated with a 12% lower risk for type 2 diabetes.
Rahimi et al conclude: “The evidence that blood pressure reduction is linked to diabetes presents clinicians and health policy makers with an opportunity to modify disease risk, for instance, either through the use of appropriate antihypertensive medications or by promoting lifestyle behaviours known to reduce blood pressure such as by maintaining a healthy weight through physical activity and a balanced diet.”
In a linked comment, Matthew Cavender and Robert Wirka, both from the University of North Carolina at Chapel Hill in the USA, say that although the absolute diabetes risk reduction is modest, “interventions with small benefits can have an outsized effect when applied to conditions as common as hypertension.”
They believe that the study “supports the possibility that earlier, more aggressive lowering of blood pressure, with an emphasis on RAS [renin–angiotensin system] inhibitors, can decrease the incidence of diabetes.”
The commentators also question whether “these data are enough to encourage the writers of the hypertension guidelines in the USA to follow the lead of the European Society of Cardiology to make RAS inhibitors the first-line hypertension treatment for all patients and not just in those with albuminuria.”
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