The annual prevalence of diabetes mellitus increased from 2.8% (565 patients) to 3.8% (734 patients). When guidelines emphasised diet treatment, treatment with diet only increased and oral pharmacological treatment decreased. When guidelines emphasised better glycaemic control, diet only decreased and biguanide treatment increased, and when guidelines emphasised vigorous glycaemic control, treatment with diet only decreased further and sulphonylurea and insulin use increased