Healthy lifestyle is best for long term prevention of diabetes

A 10 year follow-up of a randomised trial that compared healthy lifestyle, metformin, and placebo shows that a healthy lifestyle is the best way to prevent diabetes in the long run⇑. The original trial recruited 3819 people with raised fasting plasma glucose, impaired glucose tolerance, and overweight. After three years, the lifestyle intervention—which was designed to help people lose 7% of their weight and achieve at least 150 minutes each week of moderate intensity physical activity—reduced the incidence of diabetes by 58% compared with placebo; metformin reduced the incidence by 31%.

After a one to two week drug washout study for people randomised to metformin or placebo, a group lifestyle intervention—which was similar to the lifestyle intervention in the original trial but did not offer individualised problem solving and behaviour change support—was offered to all participants during the one year bridge period. Finally, for the remaining time of the study, a lifestyle session was offered to all participants every three months, and people originally assigned to metformin continued to take it.

Although no further differences in weight or incidence of diabetes were seen between the groups in the years after the original trial ended, the benefits of the lifestyle intervention were sustained at 10 years after randomisation, with a 34% reduction in the incidence of diabetes compared with placebo; this was 18% for metformin. On average, diabetes was delayed by four years with lifestyle and by two years with metformin.

The linked editorial (doi:10.1016/S0140-6736(09)61457-4) points to a rise in the incidence of diabetes in the metformin group during the bridge period and says it is still not clear whether metformin is masking, suppressing, or delaying diabetes. Other questions remain unanswered, such as the cost effectiveness of prescribing metformin for a decade to delay the onset of diabetes …