Adherence/maintenance intervention
The maintenance program used in the DPP was more intensive than that used in other clinical trials (6,7) and combined both group and individual contact. After completing the 16-session core curriculum, the protocol required that participants be seen face-to-face at least once every 2 months for the remainder of the trial and be contacted by phone at least once between visits. Although these in-person contacts were usually one-on-one, they could occur in a group as long as there was an opportunity to weigh the participant and assist the individual with problem-solving regarding adherence.