Approximately a quarter of adults with type 1 diabetes do not succeed in achieving satisfactory glycaemic control, partly due to problems with the demanding self-management regimen. To improve glycaemic control, interventions with a cognitive behavioural approach, aimed at modifying dysfunctional beliefs, reducing negative emotions and enhancing self-care practices are a potentially successful tool. Little is known about the reach of such an approach. This article describes characteristics of participants in a randomized, controlled trial of cognitive behavioural group training for patients with type 1 diabetes in poor glycaemic control. Results show that outpatients from seven hospitals in the area of Amsterdam, selected on long-standing high HbA1c and volunteering to participate, report high levels of psychological distress and depressive symptoms. Furthermore, self-care behaviours were perceived as important, but burdensome. Diabetes-specific self-efficacy was relatively low. It is concluded that this selected group of adults with type 1 diabetes would potentially benefit from a cognitive-behavioural intervention in order to reduce negative emotions, enhance diabetes self-efficacy, self-care behaviour and glycaemic outcomes.