A retrospective, semi-structured telephone interview was used to collect data from 28 of 31 families who participated in a pilot study testing subcutaneous insulin as a means to prevent or delay insulin-dependent diabetes mellitus (IDDM) onset. Interviews were conducted an average of 3 years after the initiation of the subcutaneous insulin protocol. Both the high-risk person (if > or = 8 years of age) and a family member (spouse or parent) were interviewed. Most participants reported that they were distressed to learn that they or a family member were at risk for IDDM, and families readily agreed to initiate subcutaneous insulin therapy. More children than adults reported insulin injections and blood glucose tests were "hard" or "very hard," but noncompliance was more common in adults. Of the high-risk participants interviewed, 58% of children and 100% of adults reported experiencing hypoglycemia, although episodes requiring someone else's assistance were rare, occurring in 38% of the children and 27% of the adults. Participants remained enthusiastic about trial participation; most favored screening programs to identify those at risk for IDDM, believed screening should be conducted regardless of age, believed subcutaneous insulin prevented or delayed IDDM onset, and would recommend subcutaneous insulin therapy to another high-risk individual. In addition, more than 40% of children, parents, and spouses reported that they would have benefited from access to a mental health professional at some point during the trial.