Technology continues to be a significant adjunct in the management of chronic illness, even more so in people with diabetes. A recent article by Konoff et. al. "Continuous Glucose Monitoring: An Endocrine Society Clinical Practice Guideline," published in The Journal of Clinical Endocrinology and Metabolism summarized the benefits of CGM in adults, children, and adolescents. The purpose of the paper was to "formulate practice guidelines for determining settings where patients are most likely to benefit from the use of continuous glucose monitoring." A task force was developed to include diabetes experts, a methodologist, and a medical writer. "An evidence-based guideline was developed using the Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) system to describe both the strength of recommendations and the quality of evidence."
The task force evaluated three potential applications of continuous glucose monitoring relying on evidence-based literature in which there was enough data to recommend the use of CGM:
1. Real-time outpatient CGM in children at least 8 years of age and adolescents
2. Real-time outpatient CGM in adults
3. Real-time inpatient CGM in adults
The guidelines also suggested intermittent "diagnostic" application of CGM in both children and adults to analyze blood glucose patterns overnight (low blood sugars, dawn phenomena) and post-meal hyperglycemia. The data did not support the use of CGM in the intensive care unit or operating room until there is a further supporting documentation.
Based on the above recommendations, several questions must be asked:
1. Should all children (older than 8 years of age), adolescents, and adults with diabetes begin continuous glucose monitoring?
2. Should insurance carriers assume the cost of this equipment?
3. Should users of CGM wear the monitor all the time, intermittently, once a week, once a month, etc.?
4. Are CGM's necessary to enable successful management of diabetes?
Let's review how CGM really works. The CGM requires a sensor to be placed subcutaneously that measures the glucose in interstitial fluid (not blood) continuously but lags approximately 20-30 minutes behind serum glucose levels. The CMG graphically demonstrates interstitial glucose trends with arrows revealing upward, stable, and downward fluctuations of blood sugars. The CGM is not meant to replace self blood glucose monitoring, rather the purpose is to alert the user to check blood sugars more appropriately at times where the system is noting significant fluctuations upward or downward. SBGM is always recommended prior to eating in order to correctly calculate a correction bolus in addition to the food bolus. In summary, the CGM, at present, measures interstitial glucose trends as a proxy for blood glucose, but does not communicate with an insulin pump providing appropriate directions for insulin administration. YET. Research is actively underway to provide a closed feedback loop to marry the CGM with the insulin pump. Prototypes are in progress using different algorithms to make the unification of blood glucose and insulin therapy a reality (artificial pancreas).
