The procedure – using a plastic liner in the gut – either cleared the condition or made its effect much milder.
It could also end the need for painful daily insulin injections.
Results from the ground-breaking treatment have been so encouraging experts last night called for surgery to be “fully recognised” as an option for Type 2 diabetes.
Under the procedure, patients have the plastic liner fitted into the stomach to stop the walls of the upper gut coming into contact with food. It blocks key hormones entering the blood.
Professor Francesco Rubino, who is leading the research at King’s College Hospital in London, said: “In many patients, blood sugar levels go back to normal within days.”
The trials offer fresh hope to the four million people living with lifestyle driven Type 2 diabetes.
Prof Rubino added: “About 50 per cent of patients are diabetes free after these procedures. The remaining people demonstrate big improvements of blood sugar control and can drastically reduce their dependence on insulin or other medication.”
The trials are taking place at King’s and University College Hospital and City Hospital in Birmingham, Britain’s “diabetes capital”.
The flexible plastic stomach sleeves were developed to mimic the effects of a gastric bypass without surgery and have been approved for clinical use in Europe and South America.
In British trials, patients fitted with the 23½inch-long “EndoBarrier” sleeve have seen marked improvement in symptoms.
Those fitted with it had lived with Type 2 for 12 years on average and usual treatments, including diet and medications, had failed to bring the condition under control.
After a year researchers found 25 people given the sleeve had lost nearly 2½st each, slashed their blood pressure and controlled better blood glucose levels. Six no longer needed insulin jabs.
Nurse Andrea Midmer, 59, who weighed 20st and was on insulin before she underwent surgery, said: “The effect was immediate….