Lowering high blood pressure is an effective way of reducing someone’s risk of developing type 2 diabetes, research suggests.
Blood pressure-lowering drugs are already prescribed to lower an individual’s chance of a life-threatening heart attack or stroke, but until now it had not been known whether the medications can help stave off diabetes.
A new study reveals the drugs’ protective effects are wider than previously thought and may directly reduce the risk of type 2 diabetes.
In the UK 13.6 million people are estimated to be at high risk of developing the condition.
In a study of more than 145,000 people from 19 randomised clinical trials across the world, researchers at the universities of Oxford and Bristol found that a 5 mmHg reduction in systolic blood pressure – easily achieved through blood pressure-lowering drugs or lifestyle changes – reduced the risk of type 2 diabetes by 11%.
Participants were followed up for an average of 4.5 years and 9,883 people developed type 2 diabetes.
Researchers say the reduction was confirmed using genetic data analysis.
People with genetically influenced lower blood pressure levels had a 12% lower risk of type 2 diabetes, compared with those without the genetic associations.
The researchers then investigated the effects of five major types of blood pressure drugs from 22 clinical trials compared with a placebo.
They found angiotensin-converting enzyme (ACE) inhibitors and angiotensin receptor-II blockers (ARBs) had the strongest protective effect, reducing the relative risk of developing diabetes by 16%.
Other types of blood pressure-lowering drugs were not protective, the study said.
It also found that calcium channel blockers had no effect on diabetes risk, while beta-blockers and thiazide diuretics increased the risk despite their known beneficial effects in preventing heart attacks and strokes.
This risk is already known and doctors consider it when prescribing these drugs.
The researchers suggest the opposing effect of different types of drugs on diabetes risk is most likely to be due to the different ways they act in the human body, independent of their ability to lower blood pressure.
Scientists say these results from clinical trials and genetic studies have shown that lowering blood pressure can prevent type 2 diabetes at a similar scale already known to prevent major cardiovascular disease.
They suggest existing drugs – particularly ACE inhibitors and ARBs – should be considered in the treatment plan for some patients at higher risk of type 2 diabetes.
Professor Kazem Rahimi, lead researcher of the study at the University of Oxford and a consultant cardiologist, said: “Current clinical guidelines do 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.”
Professor Sir Nilesh Samani, medical director at the British Heart Foundation, which funded the research, said: “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.
“It also shows that different commonly used drugs for lowering blood pressure have very different effects on risk of diabetes.
“Doctors should therefore consider the patient’s risk of developing diabetes when they are choosing an anti-hypertensive drug to lower their blood pressure.”
The research, published in The Lancet, was also funded by the National Institute for Health Research (NIHR) Oxford Biomedical Research Centre and the Oxford Martin School.