Aims: The purpose of this study was to examine how prevention of complications for people with diabetes mellitus had been conducted, as described in their medical records, focusing particularly on sudden cardiac death. A further aim was to compare the documentation with guidelines for diabetes care. Background: Diabetes mellitus is associated with an increased risk of cardiovascular disease, death and sudden cardiac death. About half of those affected by sudden cardiac death are assumed to have had one or more risk factors for cardiovascular disease that could have been treated effectively resulting in a reduced risk of sudden death. Design: Survey. Method: Fifty-six people diagnosed with diabetes mellitus, who had died of a sudden cardiac arrest between the years 2003-2005, from the Northern Sweden MONICA myocardial registry were included. These people's medical records were examined with regard to documentation of the care given during the year prior to the person's sudden cardiac death. Results: The qualitative content analysis resulted in four categories: individualised goals for diabetes care; prevention of complications; self-care; and factors which may affect ability to adhere to treatment. The quantitative analysis showed that few people with diabetes mellitus achieved goals for metabolic control, compared with those set in guidelines for diabetes mellitus care.Conclusion. To prevent complications for people with diabetes mellitus, it is a challenge for nurses and physicians to involve people with diabetes mellitus in their own care to improve the prognosis. Relevance to clinical practice: Examination of medical records of people with diabetes mellitus showed that documentation could be more informative and systematic. It is important to achieve better adherence to treatment and to increase people's understanding of their illness. © 2010 Blackwell Publishing Ltd.