Blood pressure lowering can help prevent patients developing type 2 diabetes, UK research shows for the first time.

A 5mmHg reduction in systolic blood pressure reduced the risk of diabetes by 11%, researchers found in an analysis of large-scale individual participant data from 19 blood pressure lowering randomised controlled trials.

The trials included a total of 145,939 people who were followed up for an average of 4.5 years, with 9,883 people developing type 2 diabetes.

The risk reduction was confirmed using Mendelian randomisation, which uses naturally occurring genetic differences to randomly divide participants into groups, mimicking the effects of running a clinical trial. This found people with genetically influenced lower blood pressure levels had a 12 % lower risk of type 2 diabetes, compared with those without the genetic associations.

Finally, the research team analysed the effects of specific antihypertensive drug classes using results from 22 studies and found angiotensin-converting enzyme (ACE) inhibitors and angiotensin II receptor blockers (ARBs) had the strongest protective effect on the risk of diabetes.

No effect was found with calcium channel blockers, while beta-blockers and thiazide diuretics increased the risk, the research team reported in The Lancet.

‘This study suggests that blood pressure lowering can help prevent diabetes in addition to its well-established beneficial effects in reducing cardiovascular events,’ they wrote.

‘The relative magnitude of reduction per 5 mm Hg systolic blood pressure lowering was similar to those reported for prevention of major cardiovascular events.’

ACE inhibitors and ARBs should become the drugs of choice for blood pressure lowering when a patient is considered at risk of diabetes, they added, while beta-blockers and thiazide diuretics should be avoided where possible.

Consultant cardiologist and study lead author Professor Kazem Rahimi of the University of Oxford said that current clinical guidelines did not provide clear recommendations on lowering blood pressure as a strategy to prevent type 2 diabetes.

‘Our research provides clear evidence that giving ACE inhibitors or ARBs, which are widely available and affordable worldwide, to patients at high risk could curb the growing burden of type 2 diabetes,’ he said.

The study was funded by the British Heart Foundation, the National Institute for Health Research (NIHR) Oxford Biomedical Research Centre and the Oxford Martin School.

Professor Sir Nilesh Samani, British Heart Foundation medical director, said clinicians should consider a patient’s risk of developing diabetes when choosing an anti-hypertensive to lower blood pressure.

‘Diabetes and high blood pressure are two important and growing problems which increase a person’s chance of developing an array of other serious health complications, including heart attacks and strokes. This research shows that the two are inter-connected and that lowering blood pressure could be a powerful way to reduce the risk of developing diabetes,’ he said.