One in eight people in the world will have type 2 diabetes by 2045 if obesity continues to climb at the present rate, according to a new study.

Last year, 14% of the global population was obese and 9% had type 2 diabetes. By 2045, 22% will be obese and 12% will be suffering from type 2 diabetes, estimates presented at the European Congress on Obesity in Vienna suggest.

The implications of the expanding numbers are severe for health systems in every country. Diabetes UK estimates that the NHS spends £14bn a year on the disease already, which is about 10% of its budget. People with diabetes need monitoring, treatment and care for the serious potential complications which can include amputations and blindness.

The study was carried out by scientists funded by the pharmaceutical company Novo Nordisk, which makes diabetes treatments, together with the Steno Diabetes Centre in Gentofte, Denmark, and University College London. They say that to prevent type 2 diabetes rates rising above 10%, obesity levels must come down by a quarter.

The institutions collaborated to launch the Cities Changing Diabetes programme in 2014 to accelerate the global fight against urban diabetes. The program began with eight cities: Copenhagen, Rome, Houston, Johannesburg, Vancouver, Mexico City, Tianjin and Shanghai. These have since been joined by a further seven cities: Beijing, Buenos Aires, Hangzhou, Koriyama, Leicester, Mérida and Xiamen.

“These numbers underline the staggering challenge the world will face in the future in terms of numbers of people who are obese, or have type 2 diabetes, or both. As well as the medical challenges these people will face, the costs to countries’ health systems will be enormous,” said Dr Alan Moses of Novo Nordisk Research and Development in Søborg, Denmark.

“The global prevalence of obesity and diabetes is projected to increase dramatically unless prevention of obesity is significantly intensified. Developing effective global programs to reduce obesity offer the best opportunity to slow or stabilise the unsustainable prevalence of diabetes. The first step must be the recognition of the challenge that obesity presents and the mobilisation of social service and disease prevention resources to slow the progression of these two conditions.”

The researchers have calculated the likely rise in obesity for individual countries. If current trends in the US continue, obesity will increase from 39% in 2017 to 55% in 2045, and diabetes rates from 14% to 18%. To keep diabetes rates in the US stable between 2017 and 2045, obesity must fall from 38% today to 28%.

In the UK, they say, current trends predict that obesity will rise from 32% today to 48% in 2045, while diabetes levels will rise from 10.2% to 12.6%, a 28% rise. To stabilise UK diabetes rates at 10%, obesity prevalence must fall from 32% to 24%.

“Each country is different based on unique genetic, social and environmental conditions which is why there is no ‘one size fits all’ approach that will work. Individual countries must work on the best strategy for them,” said Moses.

The tide could be turned, he said, “but it will take aggressive and coordinated action to reduce obesity and individual cities should play a key role in confronting the issues around obesity.”