Billions of pounds each year are being spent on “potentially preventable complications” of diabetes, researchers have said, and the condition is “very costly to the NHS”.

The health service should shift its focus “from crisis to preventative care” to reduce harm to patients living with the condition and also bring costs down, experts suggested.

Diabetes UK estimates that more than 4.4 million people in the UK are living with diabetes, and a further 1.2 million could have undiagnosed type 2 diabetes.

Research commissioned by the charity, which was carried out by the York Health Economics Consortium at the University of York, estimated the direct cost of diabetes to the NHS was about £10.7 billion in 2021/22, up from £9.8 billion in 2012.

Some 80% of costs 12 years ago were down to diabetes-related complications, such as problems with the kidneys, eyes and circulation, and nerve damage, but improvements in glycaemic control reduced this figure.

In 2021, about £6.2 billion was still being spent on “potentially preventable complications” each year, Diabetes UK suggested.

The remainder, about £4.4 billion, was spent on diagnosis, GP appointments, eye screening, blood tests, medication, support programmes and specialist diabetes team.

Academics urged health commissioners to “continue to invest in diabetes prevention, care and treatment to reduce future costs of complications with population-level interventions in addition to individual approaches”.

Colette Marshall, chief executive of Diabetes UK, said the research “paints a stark picture”.

“These complications cause untold hardship to many thousands of people and are, in most cases, preventable with the right care,” she added

“Getting care right for people with diabetes can save limbs, sight and lives. But despite some progress, too many people are still missing out and too many are developing diabetes complications.

“Shifting the dial from crisis to preventative care would help to reduce the harm from diabetes, allowing people with the condition to live well while, ultimately, reducing the cost to the health service.”

Last year academics said diabetes cases are likely to “grow aggressively” in every country and among every age group.

A paper published in the Lancet Diabetes and Endocrinology journal said that by 2050, some 1.3 billion people will have diabetes, more than double the 529 million cases in 2021.

Earlier this month, NHS England chief executive Amanda Pritchard said that the number of people under 40 at risk of developing type 2 diabetes rose by a quarter last year.

The latest National Diabetes Audit found 3.6 million patients registered with a GP were found to have pre-diabetes – when blood sugar is above normal range, but not high enough to be diagnosed with the condition – in 2023.

This is an increase of 549,000, or 18%, on the previous 12 months.

The figure increased by almost a quarter in those under the age of 40, from 173,166 in 2022 to 216,440 last year.

Nick Hex, associate director for the NHS and public sector at the York Health Economics Consortium, said: “Diabetes is a debilitating and serious condition that affects people on a daily basis on many different levels.

“It remains very costly to the NHS, and the majority of those costs are still spent on potentially preventable complications.

“Increased investment in new medicines and technologies that help people better manage their condition contribute to some of the high ongoing costs, but the rise in type 2 diabetes in under 40s is a particular concern and there needs to be continued focus on prevention strategies.”

Kim Steer, 56, from Yeovil, Somerset, was diagnosed with type 1 diabetes when she was 19.

She has diabetic retinopathy, an eye disease that develops if your blood glucose levels and blood pressure are consistently high.

Ms Steer, who is a teacher, said: “Because of my diabetes, I have lost some of my sight. These complications came as a big shock and I have had to make some big adjustments, as I need to be able to continue with my teaching.

“I was being told that if I don’t keep my blood sugar levels to my targets, this would affect my vision and I’d lose more sight. But for a while I wasn’t getting the support I needed to help me do that.”

Ms Steer has since been provided with a continuous glucose monitor by the NHS to help manage the condition.

She described it as “such a turnaround”, adding: “My eyes have stabilised and I’m no longer being seen at the hospital every couple of months.”

An NHS spokesperson said: “More than 1.6 million people in England have benefited from the NHS’ Diabetes Prevention programme, while our world-leading Path to Remission programme, which includes soups and shakes diet replacements, is helping thousands of people with diabetes to improve their health.

“The NHS is also offering people under 40 with early onset type 2 diabetes targeted interventions such as weight management support, managing blood sugar level, and support with unmet psychological or social needs – so if you are concerned about your health, you can easily check your risk through the Diabetes UK ‘Know Your Risk’ tool and come forward for support.”