Do Glucose-Lowering Interventions Prevent Retinopathy in Patients with Prediabetes?

In the randomized Diabetes Prevention Program (DPP), adults with prediabetes and overweight (body-mass index, ≥24 kg/m²) received intensive lifestyle modification, metformin, or placebo (NEJM JW Gen Med Mar 15 2002 and N Engl J Med 2002; 346:393). Both active-intervention groups were less likely than controls to meet glycemic criteria for diabetes at 3 years, but the ultimate question was whether this laboratory outcome eventually would translate into better long-term clinical outcomes.

To address that question, the DPP researchers initiated a long-term follow-up study (the DPP Outcome Study) in which patients in the original metformin group were offered ongoing metformin, and those in the original lifestyle-intervention group were offered r…