Physical activity and body mass index (BMI) are linked to the prevention and management of type 2 diabetes (T2D). Romantic partners influence each other's health and the behavioral management of T2D often involves both partners. Therefore, this study examined dyadic associations between physical activity and BMI in couples in which one partner has T2D. Data came from the Lifelines cohort study. The actor-partner interdependence model was applied to cross-sectional data from 1133 couples in which only one partner had T2D. The physical activity of the person with diabetes was inversely associated with his/her partner's BMI. However, partner physical activity was not associated with the BMI of the person with diabetes. These results suggest that people with diabetes may influence the BMI of their partners. Future research should consider how people with diabetes influence the health outcomes of their partners, which is an area that is often overlooked in the literature.
Keywords: Actor–partner interdependence model; Body mass index; Dyadic; Physical activity; Type 2 diabetes.