Diabetes mellitus type 2 (T2DM) is a global pandemic that will affect 300 million people in the next decade. It has been shown that early and aggressive treatment of T2DM from the onset decreases complications, and the patient's active role is necessary to achieve better glycemic control. In order to achieve glycemic control targets, an active attitude in patients is needed, and self-monitoring of blood glucose (SMBG) plays a significant role. Nowadays, SMBG has become an important component of modern therapy for diabetes mellitus, and is even more useful if it is performed in a structured way. SMBG aids physicians and patients to achieve a specific level of glycemic control and to prevent hypoglycemia. In addition, SMBG empowers patients to achieve nutritional and physical activity goals, and helps physicians to optimize the different hypoglycemic therapies as demonstrated in the St Carlos study. This article describes the different ways of using this educational and therapeutic tool from the medical point of view as well as from the patient's perspective.