In a diverse sample of 452 adult diabetes patients, we investigated: (1) personal model dimensions for diabetes and expanded upon the literature by indexing fatalism, (2) the relationship between contextual factors and patients' beliefs about the seriousness and controllability of diabetes, and (3) the unique contribution of illness representation combinations to clinical outcomes when controlling for baseline disease severity. Major categories of predictors included patients' sociocultural characteristics, illness history (e.g., co-morbidities, diabetes complications) and recent physical symptoms. Illness representations were measured using the Personal Models of Diabetes Interview and questions that index fatalistic beliefs. Clinical outcome measures included patients' glycemic control (HbA1c) and the patient's physical and mental functions as measured by the SF-12. Analyses corroborated the literature by identifying seriousness and treatment effectiveness cognitive model dimensions for diabetes. Physical symptoms and other disease-related factors were strong predictors of patients' seriousness beliefs for diabetes, whereas sociocultural factors (education, ethnicity) best explained representations related to the controllability of diabetes (i.e., treatment effectiveness, fatalism). Seriousness beliefs were good indicators of actual glucose control, except for cases in which patients were more fatalistic and believed diabetes to be less serious. Although patients had medically consistent views of their diabetes, variations in personal models of diabetes were related to specific contextual factors and independently explained diabetes control.