During the DPPOS, metformin participants taking study-provided metformin received an annual complete blood count and serum creatinine for drug safetymonitoring. Participants were encouraged to see their personal physicians for treatment of emergent adverse events. Only metformin participants were encouraged to take metformin, and only 1%of nondiabetic participants in lifestyle and 3% of nondiabetic participants in placebo took metformin
prescribed outside the study (4). For the purposes of this analysis, we assumed that years 5–10 represented DPPOS follow-up. Interventions for participants who developed diabetes. Participants identified with glucose levels diagnostic of diabetes at their 6-monthly visits were seen within 6 weeks for glucose testing to confirm the diagnosis. Participants with confirmed newly diagnosed diabetes received 1 h of
individual counseling focused on selfmonitoring of blood glucose, were provided with meters and test strips and encouraged to monitor their glucose levels once daily, and were maintained in their randomized
intervention groups. Treatment for diabetes and surveillance for complications and comorbidities were performed by the participants’ own health care providers. Medications used by the DPP participants for management of diabetes were recorded every 6 months on a drug summary form.