Self-monitoring of blood glucose has been used for many years to control glucose levels in diabetic patients. This method is a quick and easy way for taking pre/postprandial and pre-sleep glucose measurements and it is very simple for most of the patients. However, it does not allow collecting detailed information about excursions of hyperglycemia or hypoglycemia since most of the samples are widely spaced in time, which leads to lose important information for the treatment of diabetes. Nowadays, Continuous Glucose Monitoring System (CGMS) is used to solve such problem. CGMS devices take blood glucose samples continuously (normally every 5 minutes) from patients having type 1 or type 2 diabetes. This paper presents a literature review exploring the current CGMS applications and the role of this signal in the identification of risk factor for diabetic patients.