The main purpose of this study is to investigate the role of medical information in buffering the effect of illness symptoms on diabetic patients' stress. The data were collected by administering questionnaire interviews with 172 diabetic patients who visited or were hospitalized at Severance Hospital or Wonjoo medical center. This paper, at first, examines the dimensions of stress. Using factor analysis, I find that stress has three components: 1) internal mood; 2) external mood; 3) malaise. Second, I examine the interaction effect of medical information with illness symptoms on stress. Results from regression analysis with interaction terms indicate: 1) that as the number of illness symptoms increase, stress level increases for patients with low level of medical information; 2) that as the number of illness symptoms increase, stress level decreases slightly for patients with high level of medical information. This paper shows clearly the stress buffering effect of medical information.