Supplementary Table 4 summarizes the undiscounted, per capita, cumulative, 10-year direct nonmedical costs by intervention group and type defined as dietrelated costs, physical activity–related costs, transportation-related costs, and participant time-related costs. Diet-related costs were substantial but did not differ
among intervention groups. As might be expected, physical activity–related costs were greatest for lifestyle. Transportationrelated costs were also substantially higher for lifestyle and metformin due to the greater number of study visits. Total diet-, physical activity-, and transportationrelated costs were greatest for lifestyle but similar for metformin and placebo. Participant time contributed substantially to direct nonmedical costs. Participant time related to the interventions (time spent traveling to study visits, at study visits, and for intervention-related calls) was greater for lifestyle and metformin than for placebo. Participant time related to medical care outside of the interventions was generally greater for placebo than for metformin or lifestyle. Time spent shopping and cooking was the largest component of participant time but differed little across intervention groups. Although lifestyle subjects spent more time exercising, the adjusted value of the time they spent exercising was less than for either metformin or placebo because of their greater enjoyment of leisure time physical activity and the lower opportunity cost. The total, per capita, 10-year, direct nonmedical costsdincluding the costs of
participant timedwere lowest for metformin ($143,504) and similar for placebo and lifestyle ($146,124 and $146,930, respectively).