Blood pressure drugs could prevent millions of people worldwide from developing type 2 diabetes, a large study suggests.

Lowering high blood pressure is an effective way to slash the risk of the disease in the future, according to the research published in the Lancet.

Doctors already prescribe cheap blood pressure drugs to reduce the chances of a life-threatening heart attack or stroke. However, until now, the question of whether these drugs could also help fend off the threat of type 2 diabetes had been unanswered.

Now researchers have found the protective effects of the drugs are much wider than previously thought. The study shows they may directly reduce someone’s risk of type 2 diabetes, a condition that an estimated 13.6 million people in the UK are at high risk of developing.

In the largest study of its kind, researchers at the universities of Oxford and Bristol followed more than 145,000 people from 19 global randomised clinical trials for an average of about five years.

They found that a 5 mmHg reduction in systolic blood pressure – easy to achieve via blood pressure drugs or lifestyle changes – reduced the risk of type 2 diabetes by 11%.

Researchers also 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 II receptor blockers (ARBs) had the strongest protective effect, both reducing someone’s relative risk of developing diabetes by 16%.

Other types of blood pressure-lowering drugs were not protective. Calcium channel blockers had no effect on type 2 diabetes risk, while beta blockers and thiazide diuretics actually increased the risk despite their known beneficial effects in preventing heart attacks and strokes.

Currently, health experts say being a healthy weight and adopting a healthy lifestyle is the best way to reduce the risk of type 2 diabetes. Researchers say existing drugs – particularly ACE inhibitors and ARBs – should now be considered for some patients who are at higher risk of the disease.

Prof Kazem Rahimi, lead researcher of the study at the University of Oxford and a consultant cardiologist, said: “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.”

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

Prof Sir Nilesh Samani, the BHF medical director, 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.”