Design of a randomized trial of diabetes genetic risk testing to motivate behavior change: The Genetic Counseling/Lifestyle Change (GC/LC) Study for Diabetes Prevention

Background The efficacy of diabetes genetic risk testing to motivate behavior change for diabetes prevention is currently unknown. Purpose This paper presents key issues in the design and implementation of one of the first randomized trials (The Genetic Counseling/Lifestyle Change (GC/LC) Study for Diabetes Prevention) to test whether knowledge of diabetes genetic risk can motivate patients to adopt healthier behaviors. Methods Because individuals may react differently to receiving ‘higher ’ vs ‘lower’ genetic risk results, we designed a 3-arm parallel group study to separately test the hypotheses that: (1) patients receiving ‘higher ’ diabetes genetic risk results will increase healthy behaviors compared to untested controls, and (2) patients receiving ‘lower ’ diabetes genetic risk results will decrease healthy behaviors compared to untested controls. In this paper we describe several challenges to implementing this study, including: (1) the application of a novel diabetes risk score derived from genetic epidemiology studies to a clinical population, (2) the use of the principle of Mendelian randomization to efficiently exclude ‘average ’ diabete