Predictors of exercise intervention dropout in sedentary individuals with type 2 diabetes

PURPOSE: While the benefits of exercise in people with type 2 diabetes mellitus is well-known, knowledge of factors associated with dropouts of exercise intervention trials is limited. Examining clinical and psychosocial factors related to dropout is a necessary first step to developing an effective exercise program. We examined the predictors of a randomized trial of exercise intervention dropout among sedentary individuals with type 2 diabetes mellitus. METHODS: Participants (n = 140) were randomly allocated to a 6-month, 3 times per week exercise intervention, or to a control group. Psychological well-being was assessed using a 36-item Short Form Health Survey, the Profile of Mood States questionnaire, and an Exercise Self-Efficacy scale. Total percent body fat and abdominal subcutaneous and visceral fat were measured. Insulin resistance was assessed with the quantitative insulin sensitivity check index. Fitness was expressed as VO2 peak during treadmill testing. RESULTS: There were significantly more dropouts in the exercise group than in the control group (r = 20.220; P < .01). Those who dropped out of the study had less exercise self-efficacy for lifting weight (r = 0.187; P < .05). Physiological parameters associated with dropouts included low fitness (r = 0.255; P < .01), higher insulin resistance (r = 0.167; P < .05), higher total percent body fat (r = 20.213; P < .05), and higher subcutaneous abdominal fat (r = 20.220; P < .05). In the multiple logistic regression model, exercise group assignment, insulin resistance, and fitness remained significant predictors of dropouts. CONCLUSIONS: Special attention to the sedentary individuals with high insulin resistance and poor fitness should be incorporated into implementing exercise programs to improve diabetes treatment.