Sugar-sweetened drinks such as colas and lemonades may play a part in the alarming rise of type 2 diabetes in the UK and the US, according to new research – regardless of whether people are obese or not.

Researchers from Cambridge University said they also found a link, albeit weak, between type 2 diabetes and people who drink fruit juices or “diet” drinks containing artificial sweeteners. These are not a good substitute for sugar-sweetened drinks, they say. “Unsweetened coffee and tea or water may be the healthy option,” said Fumiaki Imamura, from the Medical Research Council epidemiology unit at the University of Cambridge School of Clinical Medicine.

The paper follows the final recommendations of the government’s scientific advisory committee on nutrition (SACN), which on Friday urged a cut in added sugar consumption to no more than 5% of a person’s diet. In particular, the independent advisers said, people should cut down on the amount of sugar-sweetened fizzy drinks, soft drinks and squash they consume.

The Cambridge team, who have published their research in the British Medical Journal, say they cannot prove that too many sweetened drinks causes type 2 diabetes from the evidence they were able to gather. But, if one assumes causality, “the current consumption of sugar sweetened beverages was estimated to cause approximately 2m excess events of type 2 diabetes in the USA and 80,000 in the UK over 10 years. This could cost nearly £12bn in the USA and £206m in the UK,” they write.

Links between obesity and type 2 diabetes are largely accepted. The researchers wanted to know whether the drinks alone could cause the condition. There are plausible biological mechanisms, they say, because a big sugar intake from a drink pushes up blood glucose levels very quickly, making it harder for the body to cope.

For the BMJ paper, they analysed the results of 17 separate observational studies, taking into account their design and quality to minimise bias. None was funded by industry. They found that regular drinkers of sugar-sweetened beverages were more likely to develop type 2 diabetes.

“This study adds further evidence that sugary drinks are associated with increasing the risk of type 2 diabetes, even in non-obese people, suggesting we are all vulnerable,” said Dr Aseem Malhotra, spokesperson for the campaigning group Action on Sugar. “They are linked to tens of thousands of deaths world wide from type 2 diabetes, heart disease and cancer. If these health timebombs were eliminated from the food supply, UK citizens would be in far better shape.”

Other scientists had some doubts about the calculations. Tom Sanders, professor emeritus of nutrition and dietetics at King’s College London, pointed out the findings were based on reports of people’s drinking habits several years before they were diagnosed with the disease and in the early stages of diabetes, people habitually drink more. “This might explain part of the association, particularly that with artificially sweetened drinks. It is also well known that people who are obese are more likely to use artificial sweeteners and drinks containing them,” he said.

Sanders said that the association found between sugar-sweetened drinks and type 2 diabetes in the study was a lot less than the impact of obesity or lack of exercise. “Age, obesity and physical inactivity are the main risk factors for developing type 2 diabetes, and most new cases of type 2 diabetes are recorded in people over the age of 50 years old, who are not major consumers of sugar-sweetened beverages (with exception of sugar added to tea),” he said.

Dr Alasdair Rankin, director of research at Diabetes UK, said the study “adds to evidence that sugary drinks are bad for health and can increase the risk of type 2 diabetes. This study does not, though, provide strong evidence about whether this is because of the calories they contain or if there is something else going on in the body that is leading to an increase in risk.

“We would advise people to limit the amount of sugary drinks they have as part of a healthy diet in order to reduce their risk of type 2 diabetes. There is very strong evidence that a healthy diet, together with regular physical activity, can help maintain a healthy weight and so help prevent type 2 diabetes.”