Introduction: Adaptation to changes that occur with diabetes mellitus is often accompanied by a variety of negative emotional responses, including anger, guilt, frustration, denial, and loneliness. Objective: The aim of this study was to assess psychological domain of quality of life for people with diabetes mellitus in relation to some of the socio-demographic variables. Methods: The study included 150 patients with diabetes mellitus from October 2011 until June 2012 year, using the questionnaire for quality of life of the World Health Organization (WHOQOL-BREF). Results: Mean score for psychological health domain was 56.28 (± 14.88), without statistically significant difference in relation to sex and with a statistic significant difference decreased with increasing of age (F = 6.715, p = 0.000) and increased with the level of education (F = 7.958, p = 0.000). Negative emotions, such as blue mood, despair, anxiety, depression were present in almost 1/2 of the respondents, “often” (32.7%), “very often” (11.3%) and “always” (4.0%) without statistically significant difference in relation to gender, age and level of education. Discussion: Mean scores for psychological health domain were lower in older and less educated patients. Conclusion: Negative feelings were present in all patients indicating the need for preventive action to soften and reduce these negative feelings.