While depression, anxiety, and negative affect are associated with smoking and smoking cessation outcomes in healthy individuals, these associations have not been established in smokers with chronic diseases such as diabetes mellitus, a condition which greatly increases cardiovascular disease risk. Other psychosocial variables such as stress and locus of control may also be associated with smoking but are seldom reported. We examined stress, affect, and locus of control by smoking status in patients with type 1 diabetes mellitus. Results indicated that current smokers reported significantly higher levels of perceived stress, a more negative affect, and higher powerful others locus of control compared with nonsmokers. These findings indicate that those patients who have diabetes and who smoke are at greater risk for depressive symptoms. This knowledge may aid clinicians in their attempts to help these patients quit smoking.