Giant UK programme to lower people’s blood-sugar levels really worked

A nationwide programme to prevent diabetes in England lowers blood sugar levels and promotes weight loss among the people referred to it, according to an analysis of more than two million health records¹.

The programme is one of the world’s largest efforts to reduce diabetes risk by modifying behaviour. Previous clinical trials suggested that such behavioural approaches can succeed in the controlled conditions of a research project, but the latest results provide real-world evidence of their potential when deployed across an entire country.

The study also highlights some limitations: benefits of the campaign, called the NHS Diabetes Prevention Programme, were more pronounced in men than in women, and many people who were referred to the intensive, nine-month programme did not enrol in it. “Definitely there is a role for this kind of intervention,” says Naomi Holman, an epidemiologist at the Royal College of Surgeons in Ireland in Dublin. “But we need to understand a bit more about what works in this kind of intervention for different people, and how sustained the results are.” The study was published in Nature on 15 November.

Sugar levels on the rise

Type 2 diabetes is a growing and global problem that is projected to affect 10% of the world’s adult population by 2030. The condition is often associated with obesity, but diabetes risk can also be enhanced by genetic or environmental factors.

Participants in the English programme attend a minimum of 13 sessions, during which they are counselled on how to eat a healthy diet and maintain a healthy weight. Eligibility for the programme is determined by blood sugar level: once this biomarker climbs above a certain threshold, a person is considered prediabetic and at high risk of developing diabetes.

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Epidemiologist Pascal Geldsetzer at Stanford University in California and his colleagues took advantage of that cut-off point to conduct an experiment. People with scores slightly below the threshold are rarely referred to the programme — even though there is no such sharp boundary in biological diabetes risk.

This provided a control group of people who did not receive a referral to the programme but were otherwise very similar to those who did. Geldsetzer and his colleagues gathered data for these two sets of people from one-fifth of England’s general practitioner’s offices and found that both blood sugar levels and body-mass index dropped in those who were referred to the programme, compared with those who were not.

The study did not analyse whether participants went on to develop type 2 diabetes, but even small drops in blood sugar have been associated with improvements in cardiovascular health, among other benefits, Geldsetzer says.

High drop-out rate

Overall, the outcome is similar to those found in clinical trials and smaller evaluations of prevention programmes, says Earle Chambers, an epidemiologist at the Albert Einstein College of Medicine in New York City. But the high rate of attrition from the programme is a concern, he adds: less than one-third of people who are referred to the programme actually start it, and fewer still complete it.

Many of those who do not participate in the programme are members of minority-ethnic communities that are at particularly high risk of diabetes and its complications, says Eleanor Barry, a physician who studies diabetes risk at the Nuffield Department of Primary Care Health Sciences at the University of Oxford, UK. “There is a risk of the intervention widening health inequalities between those who are able to engage — and subsequently reduce their diabetes risk — and those who are not,” she says.

Prevention programmes targeting people at high risk of diabetes are unlikely to be enough to rein in type 2 diabetes at a population level, says Holman. “This is just one piece of the jigsaw puzzle,” she says, “and that jigsaw needs to include other public-health interventions.”