In the fight against the type 2 diabetes epidemic, patients might be asked to discuss familial susceptibility to type 2 diabetes in their family. Illness representations of patients (N = 546) were assessed to explore their impact on perceived type 2 diabetes threat in relatives. Reporting high type 2 diabetes burden, emotional impact and perceiving type 2 diabetes as an inheritable disease seemed to increase patients’ family risk perception and worries about relatives’ future health. Patients with coherent illness understanding reported positive beliefs regarding type 2 diabetes prevention in relatives. Findings may give direction in how illness representations may be used to guide patients in the process of family risk disclosure.