New research suggests that half of all US adults have either type 2 diabetes or prediabetes.

The study, conducted by the US National Institute of Diabetes and Digestive and Kidney Diseases, also found that most people were unaware of their diabetes.

“Diabetes can be treated, but only if it is diagnosed,” Catherine Cowie, a program director at the institute, told US News. “The medical community needs to be aware that there is a high rate of undiagnosed diabetes in the population.”

To assess the prevalence of diabetes in the US population, the organisation used data from the US National Health and Nutrition Examination Surveys. Their analysis suggested that 14 per cent of adults have type 2 diabetes. Around 35 per cent of them are unaware of it.

The study also examined the impact of race on diabetes risk. Black people, Hispanic people, and Asian people are all twice as likely to develop type 2 diabetes than white people.

It is worth noting that 38 per cent of people are noted as having “prediabetes,” which is a heavily debated label. While it is a useful way to encourage people to make lifestyle changes, some research suggests that labelling people as prediabetic does not reduce the likelihood that they will develop type 2 diabetes. Neither are the thresholds for prediabetes adjusted for certain inevitable factors: aging, for example, which naturally increases one’s blood glucose levels.

Part of the problem with prediabetes is that it is expensive. Many people, having been diagnosed with prediabetes, will be put on diabetes medication such as metformin to lower their blood glucose levels. Critics argue that this is a waste of money; many of these people would not have gone on to develop type 2 diabetes anyway.

The institute’s findings paint a bleak picture of diabetes, but there is good news: levels of diabetes have levelled off somewhat since 2008, suggesting that, in terms of prevention, something is being done right. However, it is a small improvement for a large problem; the trend of increasing rates of diabetes, although not rising as rapidly as before, shows no signs of reversing.

The findings were published in the Journal of the American Medical Association.