Tens of thousands of people with type 1 diabetes are being put at increased risk of serious complications by “short-sighted” rationing of a blood sugar patch used by Theresa May, an investigation has found.

The prime minister is one of 400,000 type one diabetics in the UK. She told Parliament in last month that NHS patients would be prescribed the same Freestyle Libre monitor she uses to maintain a healthy blood glucose levels.

The wearable sensor which sits on the arm can feed continuous glucose levels to a smart phone or reader, doing away with the need to do the finger prick blood test.

However, NHS England’s associate national clinical director for diabetes, has said only around one in five patients who could benefit from the monitors, have access to them, one year after they first became available.

Dr Partha Kar spoke out after an investigation in the British Medical Journal (BMJ) found prescription of the monitors in England was significantly behind the other home nations. It also revealed that a number of NHS clinical commissioning groups (CCGs) have put strict restrictions on devices.

“I think some of it CCGs’ resistance] is financial," he said. “But also some people are just finding a reason to say no. One CCG said to me, ‘We don’t think the evidence is there.’ And I said, ‘Well, how is the evidence there for London, Manchester, Liverpool, Brighton but not for you? How does that work?’ That’s just ridiculous.”

He added that they were “paying lip service” to guidelines set by the National Institute of Health and Care Excellence (NICE).

Campaigners have also claimed it is compromising diabetics’ quality of life and creating extra costs for the NHS in the long-run from limb amputations and other complications of poorly controlled blood sugar.

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NICE recommends treatments for the NHS in England and has called the Libre device cost effective in many patients with severe diabetes in need of frequent monitoring.

If they were followed correctly, Dr Kar estimates as many as 25 per cent of type 1 diabetics would be prescribed the device. Currently that number is 5 per cent at most.

In some areas GPs are flouting the restrictions placed on them by their CCGs because of the transformative effect other device can have to their patients, but others face real barriers.

Dr Emma Wilmot, a consultant diabetologist in Derby said some of her patients have considered moving house to fall within the catchment area of a CCG which will prescribe the device.

NHS at 70: demonstration and celebration march to mark anniversary Show all 18 1 /18 NHS at 70: demonstration and celebration march to mark anniversary NHS at 70: demonstration and celebration march to mark anniversary People holding placards attend a demonstration and celebration march to mark the 70th anniversary of the National Health Service (NHS), in central London on June 30, 2018. Organised by the Peoples Assembly, Health Campaigns Together, The TUC and 11 other health trade unions, tens of thousands are expected to attend the only national public event organised to mark the anniversary of the British Health Service. / AFP PHOTO / Tolga AKMENTOLGA AKMEN/AFP/Getty Images TOLGA AKMEN AFP/Getty Images NHS at 70: demonstration and celebration march to mark anniversary Labour Party leader, Jeremy Corbyn, addresses demonstrators following the march AFP/Getty NHS at 70: demonstration and celebration march to mark anniversary A man stands with a coffin, used as a prop at a demonstration and celebration march to mark the 70th anniversary of the National Health Service (NHS), in central London on June 30, 2018. Organised by the Peoples Assembly, Health Campaigns Together, The TUC and 11 other health trade unions, tens of thousands are expected to attend the only national public event organised to mark the anniversary of the British Health Service. / AFP PHOTO / Tolga AKMENTOLGA AKMEN/AFP/Getty Images TOLGA AKMEN AFP/Getty Images NHS at 70: demonstration and celebration march to mark anniversary epa06851663 Thousands of people march, to mark 70 years of the British National Health Service (NHS), in central London, Britain, 30 June 2018. Reports state that the gathering is calling on the government for increased funding and staffing for the NHS, as well as a protest against privatisation of an organisation which turns 70 years old on 05 July 2018. EPA/ANDY RAIN ANDY RAIN EPA NHS at 70: demonstration and celebration march to mark anniversary People holding placards attend a demonstration and celebration march to mark the 70th anniversary of the National Health Service (NHS), in central London on June 30, 2018. Organised by the Peoples Assembly, Health Campaigns Together, The TUC and 11 other health trade unions, tens of thousands are expected to attend the only national public event organised to mark the anniversary of the British Health Service. / AFP PHOTO / Tolga AKMENTOLGA AKMEN/AFP/Getty Images TOLGA AKMEN AFP/Getty Images NHS at 70: demonstration and celebration march to mark anniversary A man wears an NHS themed hat during a march in support of the National Health Service, in central London, Britain, June 30, 2018. REUTERS/Simon Dawson SIMON DAWSON Reuters NHS at 70: demonstration and celebration march to mark anniversary Demonstrators hold placards during a march in support of the National Health Service, in central London, Britain, June 30, 2018. REUTERS/Simon Dawson SIMON DAWSON REUTERS NHS at 70: demonstration and celebration march to mark anniversary epa06851662 A man with a birthday placard as thousands of people march, to mark 70 years of the British National Health Service (NHS), in central London, Britain, 30 June 2018. Reports state that the gathering is calling on the government for increased funding and staffing for the NHS, as well as a protest against privatisation of an organisation which turns 70 years old on 05 July 2018. EPA/ANDY RAIN ANDY RAIN EPA NHS at 70: demonstration and celebration march to mark anniversary Demonstrators stand in Whitehall during a march in support of the National Health Service, in central London, Britain, June 30, 2018. REUTERS/Simon Dawson SIMON DAWSON REUTERS NHS at 70: demonstration and celebration march to mark anniversary People march in central London to mark the 70th anniversary of the NHS. PRESS ASSOCIATION Photo. Picture date: Saturday June 30, 2018. See PA story INDUSTRY Demonstration. Photo credit should read: John Stillwell/PA Wire John Stillwell PA NHS at 70: demonstration and celebration march to mark anniversary Demonstrators hold placards during of a march in support of the National Health Service, in central London, Britain, June 30, 2018. REUTERS/Simon Dawson SIMON DAWSON REUTERS NHS at 70: demonstration and celebration march to mark anniversary People holding placards attend a demonstration and celebration march to mark the 70th anniversary of the National Health Service (NHS), in central London on June 30, 2018. Organised by the Peoples Assembly, Health Campaigns Together, The TUC and 11 other health trade unions, tens of thousands are expected to attend the only national public event organised to mark the anniversary of the British Health Service. / AFP PHOTO / Tolga AKMENTOLGA AKMEN/AFP/Getty Images TOLGA AKMEN AFP/Getty Images NHS at 70: demonstration and celebration march to mark anniversary Demonstrators hold placards during a march in support of the National Health Service, in central London, Britain, June 30, 2018. REUTERS/Simon Dawson SIMON DAWSON REUTERS NHS at 70: demonstration and celebration march to mark anniversary Jeremy Corbyn and Jon Ashworth speak during a march in central London, marking the 70th anniversary of the NHS. PRESS ASSOCIATION Photo. Picture date: Saturday June 30, 2018. See PA story INDUSTRY Demonstration. Photo credit should read: John Stillwell/PA Wire John Stillwell PA NHS at 70: demonstration and celebration march to mark anniversary People holding placards attend a demonstration and celebration march to mark the 70th anniversary of the National Health Service (NHS), in central London on June 30, 2018. Organised by the Peoples Assembly, Health Campaigns Together, The TUC and 11 other health trade unions, tens of thousands are expected to attend the only national public event organised to mark the anniversary of the British Health Service. / AFP PHOTO / Tolga AKMENTOLGA AKMEN/AFP/Getty Images TOLGA AKMEN AFP/Getty Images NHS at 70: demonstration and celebration march to mark anniversary People holding placards attend a demonstration and celebration march to mark the 70th anniversary of the National Health Service (NHS), in central London on June 30, 2018. Organised by the Peoples Assembly, Health Campaigns Together, The TUC and 11 other health trade unions, tens of thousands are expected to attend the only national public event organised to mark the anniversary of the British Health Service. / AFP PHOTO / Tolga AKMENTOLGA AKMEN/AFP/Getty Images TOLGA AKMEN AFP/Getty Images NHS at 70: demonstration and celebration march to mark anniversary People gather with placards to attend a demonstration and celebration march to mark the 70th anniversary of the National Health Service (NHS), in central London on June 30, 2018. Organised by the Peoples Assembly, Health Campaigns Together, The TUC and 11 other health trade unions, tens of thousands are expected to attend the only national public event organised to mark the anniversary of the British Health Service. / AFP PHOTO / Tolga AKMENTOLGA AKMEN/AFP/Getty Images TOLGA AKMEN AFP/Getty Images NHS at 70: demonstration and celebration march to mark anniversary People gather with placards to attend a demonstration and celebration march to mark the 70th anniversary of the National Health Service (NHS), in central London on June 30, 2018. Organised by the Peoples Assembly, Health Campaigns Together, The TUC and 11 other health trade unions, tens of thousands are expected to attend the only national public event organised to mark the anniversary of the British Health Service. / AFP PHOTO / Tolga AKMENTOLGA AKMEN/AFP/Getty Images TOLGA AKMEN AFP/Getty Images

“I’ve had to say to patients, ‘I’m really sorry, you don’t meet the criteria because your GP is not in the right area.’ They are absolutely gutted. My worry is the people who aren’t in a position to self-fund it. The most deprived people in the population often have the least access.”

She added: “The reason that we strive to reduce complications is to maintain quality of life. And actually, by preventing people having access to the Libre you are compromising their quality of life compared with what it could be.”

Data disclosed to the BMJ under the Freedom of Information Act shows that some areas have invested heavily in making the devices available, but only two of 195 CCGs had prescribed to more than 20 per cent of their type 1 diabetics.

Twenty-five CCGs had issued no prescriptions at all. Diabetes campaigners claim just 2 per cent of patients in England have a GP prescription for Freestyle Libre, compared to 11 per cent in Scotland, 16 per cent in Wales and 35 per cent in Northern Ireland.