Costs
We calculated the total directmedical costs associated with the DPP/DPPOS interventions over each of the 10 years after randomization (Supplementary Table 1). Direct medical costs of the interventions were estimated from the resources used
and unit costs adjusted to 2010 U.S. dollars (Supplementary Table 2). As a sensitivity analysis, we estimated what the cost of lifestyle might have been during the DPP if it had been administered in a group format rather than individually (DPP group lifestyle intervention). We recalculated the costs of lifestyle assuming that the core curriculum and monthly follow-up visits with the lifestyle case managers, which were conducted individually during the 3 years
of the DPP, were conducted as group sessions with 10 participants. Studies have shown that group intervention programs can be as effective as individual programs(12,13). Although metformin was implemented with brand name metformin (Glucophage),we assumed that it was implemented
with generically priced metformin throughout the 10 years of the DPP/DPPOS.