Contemporary perspectives on diabetes care accord a central role to patient self-care, or self-management. Self-care implies that the patient actively monitors and responds to changing environmental and biological conditions by making adaptive adjustments in the different aspects of diabetes treatment in order to maintain adequate metabolic control and reduce the probability of complications (21). The self-care behaviours involved in achieving adequate metabolic control and avoiding long-term complications are: home glucose monitoring (in blood or urine); adjustment of food intake, especially of carbohydrates, to meet daily needs and match available insulin; administration of medication (insulin or oral hypoglycaemic agents); regular physical activity; foot care; regular medical monitoring visits, and other behaviours (i.e. dental care, appropriate clothing, etc.) that may vary depending on the type of diabetes (18).

Against this background of illness-related demands, adherence is conceptualized as the active, voluntary involvement of the patient in the management of his or her disease, by following a mutually agreed course of treatment and sharing responsibility between the patient and health care providers (22). Hentinen (23) described adherence to self-care as an active, responsible and flexible process of self-management, in which the patient strives to achieve good health by working in close collaboration with health care staff, instead of simply following rigidly prescribed rules. Other terms have been proposed such as "collaborative diabetes management" (24),"patient empowerment" (25) or "self-care behaviour management" (23,26 - 28). Another important concept is "inadvertent nonadherence" which occurs when a patient believes he or she is adhering to the recommended treatment but, through errors in knowledge or skill, is not doing so (29).