A US study published in The Lancet: Diabetes and Endocrinology has confirmed that intensive lifestyle changes and metformin therapy can reduce the long-term risk of developing type 2 diabetes in people with prediabetes. The findings come from the Diabetes Prevention Program Outcomes Study (DPPOS), which followed participants for up to 21 years after they joined the original Diabetes Prevention Program (DPP) clinical trial.

The DPP, which began in 1996, initially enrolled 3,234 adults with prediabetes. Participants were randomly assigned to one of three groups: intensive lifestyle intervention (ILS), metformin therapy (850 mg twice daily), or placebo. The original trial demonstrated a 58% reduction in diabetes risk with ILS and a 31% reduction with metformin, compared to the placebo, over three years.

The long-term follow-up study, DPPOS, continued to track 3,195 of the original participants until February 2020. During this time, the placebo group was discontinued, but the metformin group continued their medication, and the ILS group received periodic booster sessions. All participants were also offered group lifestyle classes.

Over the 21-year follow-up, the incidence of diabetes remained lower in the ILS and metformin groups compared to the original placebo group. The risk of developing diabetes was reduced by 24% with ILS and 17% with metformin. This corresponded to a median delay in diabetes onset of 3.5 years for ILS and 2.5 years for metformin. Most of the benefit came from early intervention, with differences in diabetes rates emerging within the first three years and persisting over time.

Interestingly, the benefits varied by individual characteristics. Lifestyle changes were most effective in individuals with higher fasting glucose or HbA1c levels at baseline, while younger participants derived greater benefits from metformin.
These findings underscore the value of early intervention in prediabetes and suggest that targeted approaches based on an individual's risk profile enhance prevention efforts.