The purpose of the study reported in this paper was to describe adherence to self-care, perceived difficulties and social support in a group of adult patients (n = 213) with insulin-treated diabetes from two outpatient clinics in Northern Finland. Data were collected by questionnaire. The instruments were developed to measure adherence to self-care, difficulties in self-care and social support. The response rate was 76%. One-way ANOVA, logistic regression analysis, contingency and Pearson's correlation coefficients were used in the statistical analysis. A fifth of the respondents were neglecting their self-care. The others undertook flexible, regimen-adherent or self-planned self-care. The subjects had no difficulties with insulin treatment, but had more problems with other aspects of self-care. Poor metabolic control, smoking and living alone predicted neglect of self-care, but if patients had support from family and friends, living alone was not a predictor of neglect of self-care. Those with poor metabolic control perceived themselves as getting peer support from other persons with diabetes.