The personal meaning and perceived impact of insulin dependent diabetes mellitus (IDDM) were investigated in an exploratory study of 51 Finnish adolescents aged between 13 and 17. Interview data were examined using continuous comparative analysis. The personal meaning of IDDM was described using the following categories: a habit; a little devil; a nightmare; stress; prison; death; and hell. A core concept to emerge was that of control. Young people felt IDDM controlled, or limited, their freedom and independence. Two main themes emerged in terms of the impact of IDDM in the lives of adolescents: a threat to life's equilibrium and a healthy lifestyle. Diabetes was viewed as a threat to physical, psychological and social well-being which disrupted the balance of life. In contrast, the other main category, a healthy lifestyle, revolved around the notion that having IDDM offered a unique opportunity to live a healthy life. The results provided a useful insight into the personal meaning of IDDM and serve to raise awareness of the problems and difficulties experienced by adolescents with this condition.