To investigate the effect of depression and negative attitudes on plasma glucose and complications in diabetic subjects. Methods: A total of 260 adults with diabetes completed a Diabetes Self-rating Questionaire composed of 16 items on negative attitudes to diabetes and depression. The subjects were divided into depression and non-depression groups according to depression scores. Glycemic control was assessed using fasting plasma glucose (FPG) levels and HBA1C testing. Results: The depressive mood scores were significantly correlated with FPG and HBA1C levels. The scores of negative attitude, somatic symptoms and depressive mood were significantly correlated with the number of complications. The FPG level and the number of complications had significant differences in the two groups, while the HBA1C level had no significant difference in the two groups. Conclusions: Bad emotion were significantly correlated with poor glycemic control. Depression was probably one of the factors that caused diabetes-related complications.