Diabetes experts' reasoning about diabetes prevention studies: a questionnaire survey

BACKGROUND: Presentation of results of diabetes prevention studies as relative risk reductions and the use of diagnostic categories instead of metabolic parameters leads to overestimation of effects on diabetes risk. This survey examines to what extent overestimation of diabetes prevention is related to overestimation of prevention of late complications. METHODS: Participants of two postgraduate courses in clinical diabetology in Austria (n = 69) and Germany (n = 31) were presented a questionnaire with 8 items at the beginning of the meetings. All 100 questionnaires were returned with 92 filled in completely. Participants were asked 1) to rate the importance of differently framed results of prevention studies and, for comparison, of the United Kingdom Prospective Diabetes Study (UKPDS), 2) to estimate to what extent late complications could be prevented by the achieved reductions in diabetes risk or HbA1c values, respectively. RESULTS: Prevention of diabetes by 60% was considered important by 84% of participants and 35% thought that complications could be prevented by ≥ 55%. However, if corresponding HbA1c values were presented (6.0% versus 6.1%) only 19% rated this effect important, and 12% thought that late complications could be prevented by ≥ 55%. The difference in HbA1c of 0.9% over 10 years in the UKPDS was considered important by 75% of participants and 16% thought that complications ('any diabetes related endpoint') were reduced by ≥ 55% (correct answer <15% by 20% participants). CONCLUSION: The novel key message of this study is that the misleading reporting of diabetes prevention studies results in overestimation of effects on late complications.