Lifestyle change cut diabetes risk sharply, but the effect faded once programmes ended

Every year over 3.8 million people die of diabetes and its complications, and people with impaired glucose tolerance, whose blood sugar control is already slipping, are among the most likely to progress to the full disease. Lifestyle change had long been suggested as the way to head that off. What was missing was a top-tier evidence summary pulling together the randomised trials to confirm whether it truly works. This review set out to supply exactly that.

The authors searched five major databases for randomised controlled trials in people with impaired glucose tolerance that tested a lifestyle intervention against a control group for longer than six months. Seven trials met the bar, spanning 25 publications and 5663 patients, with primary follow-up ranging from three years in India to six years in the Da Qing study. The primary outcome was new cases of diabetes; mortality, quality-adjusted life years and clinical measures such as weight and blood pressure were secondary. Reporting and methodological quality were checked with established instruments, and drop-out rates ranged from 5% to 28%.

Diabetes incidence ranged from 3% to 46% in the intervention groups against 9.3% to 67.7% in the controls. Relative risk reductions ran from 25% in the Swedish trial, which did not reach statistical significance, to 65% in the Japanese trial, with most trials landing between 29% and 58%. Several studies found the effect decreased after the intervention was terminated. Only the Da Qing study analysed deaths and cardiovascular events, and it found no statistical differences on any of them.

This review confirms what the individual landmark trials each suggested: structured lifestyle change reduces progression from impaired glucose tolerance to diabetes. It also complicates the picture in two ways, showing that benefits tend to fade once programmes end and that no long-term gain in mortality or morbidity has been demonstrated. The authors call for a standardised lifestyle programme and longer trials to test whether the early protection translates into longer, healthier lives.

If your blood sugar sits in the grey zone before diabetes, this is strong evidence that the path onwards is not fixed: across seven trials, people who changed how they ate and moved developed diabetes less often than those who did not. The fade-out after programmes ended is the other half of the message, suggesting the protection tracks the behaviour rather than banking itself permanently. That is a reason to think in terms of durable habits rather than time-limited pushes.