In this paper we examine the way in which the siblings of diabetic children react to family interaction promoting well-being (Jutras et al., 1997): this includes support behaviour, promotion of healthy lifestyles, positive interpersonal relations and therapeutic intervention. Individual interviews were conducted with 55 children (aged between 8 and 17). An analysis of the content of these interviews indicates that support behaviour and positive interpersonal relations are in the forefront. Overall, there is a symmetry or match between the way in which types of action offered and accepted by the child are perceived, though there may be asymmetry as regards the promotion of a healthy lifestyle by the mother or in the case of therapeutic acts involving the diabetic child. An analysis of the balance of exchanges shows that the mother’s and father’s input is in surplus, whereas the diabetic child is in deficit. However, a more detailed analysis of reciprocity underlines the fact that the siblings are aware of the contribution of the diabetic child to their emotional wellbeing.