Current Application of Continuous Glucose Monitoring in the Treatment of Diabetes

Abstract

The ultimate goal of diabetes technology is to create an artificial pancreas, or closed-loop system. In the early 1970s, the first prototypes became available (1). Although recent advances are promising, the closed-loop system is currently confined to the clinical research center (2). The continuous subcutaneous insulin infusion (CSII) pump became commercially available in the 1980s, and it is now a common and accepted way of providing insulin (3,4). The emergence of continuous glucose monitoring (CGM) followed in the 1990s, with the first reports on CGM by microdialysis in 1992 (5,6). Retrospective needle-type CGM systems were introduced just before the turn of the century (7–10). Currently, there are four subcutaneous CGM systems on the market that have real-time glucose values on display every 1–5 min and feature an alarm function for hypo- and hyperglycemia: the Freestyle Navigator (Abbot Diabetes Care, Alameda, CA), the Guardian Real-Time (Medtronic MiniMed, Northridge, CA), the Dexcom SEVEN (Dexcom, San Diego, CA), and the GlucoDay (Menarini Diagnostics). The first three are needle-type CGMs and the latter is a microdialysis-type sensor. All of these measure glucose via the glucose-oxidase reaction. In this article, we will discuss the pros and cons of the current application of CGM in the treatment of diabetes. From the Diabetes Control and Complications Trial and the UK Prospective Diabetes Study, we learned that lowering HbA1c reduces morbidity and mortality (11,12) and that tight glycemic control is associated with an increased rate of severe hypoglycemic episodes. We therefore should judge the pros of CGM by its HbA1c-lowering potency and its influence on severe hypoglycemia rates. Table 1 summarizes all intervention trials that have been performed with real-time CGM regarding HbA1c and the incidence of severe hypoglycemia. View this table: Table 1 CGM trials in type 1 diabetes The …