Continuous Glucose Monitors: Where are we now?
Nov 18, 2016, 10:00 AM
Continuous glucose monitoring (CGM) provides information that is not achievable using conventional finger stick blood glucose (BG) measurements. As I tell my patients, it is comparable to checking BG every 5 minutes, 24 hours per day. The recent FDA approval (July, 2016) to use CGM readings to dose for hyperglycemia (which many individuals were already choosing to do) has made this tool even more attractive. Transmitters that link to cell phones and insulin pumps make it user friendly.
The accuracy of the sensors range from +/- 9-14% depending on the make and model, which is as accurate as the FDA requirement of +/- 15% for home glucometers.
The focus of CGM has often appeared to be for individuals on insulin pump therapy, but several recent studies support use for individuals on injections (Foster 2016 and Soupol 2016) as well. In a study with 25 patients with type 2 diabetes >65 years of age on a sulfonylurea, CGM pro detected hypoglycemia 3.3% of the wear time, none detected by the individuals (Hay, 2004). Within the last 2 years, the AACE, ADA and ES all recommend CGM for patients with type 1 who are willing to wear the device on a regular basis and those particularly with hypoglycemia unawareness. This is echoed by the September 2016 task force appointed by the Endocrine Society. The committee also suggested short-term, intermittent real-time CGM use in adults with type 2 diabetes who are not on prandial insulin and have HbA1c levels ≥7%.
CGM worn on a regular basis can do the following:
- Predict and alert the individual of impending hypoglycemia allowing the patient to respond sooner and prevent severe hypoglycemia
- Be a motivational tool to improve the understanding of not only insulin quantity but timing of insulin in relationship to meals and exercise
- Help to minimize the BG excursions that have been determined to increase the risk of heart disease by providing early warnings in regards to hyperglycemia and hypoglycemia.
The cost of sensor technology is high, but the avoidance of one emergency room (ER) visit (2013 National Institute of Health study put the median cost of one visit to the ER at $1,233) would cover the cost of a transmitter and receiver. In addition, the potential for improved quality of life including reduced fear of severe hypoglycemia is hard to measure in economic terms.
Diabetes educators are poised to encourage, educate, train and support individuals who would benefit from this great technology.
Foster N, Miller K, Tamorlane W et al. Continuous glucose monitoring in patients with type 1 diabetes using insulin injections. Diabetes Care DOI.2337/dc16-00207, 2016 online.
Soupal J, Petruzelkova L, Flekac M et al. Comparison of different treatment modalities for Type 1 Diabetes, including sensor-augmented insulin regimens, in 52 weeks of follow-up: A COMISAIR Study. Diabetes Technology and Therapeutics 18(9):1-7, 2016.
Hay L, Wilmshurst E, and Fulcher G. Unrecognized hypo- and hyperglycemia in well-controlled patients with Type 2 Diabetes Mellitus: The results of continuous glucose monitoring. Diabetes Technology and Therapeutics 5(1):19-26, 2004.
About the Author:
Carla Cox is a registered dietitian and certified diabetes educator. She has been a certified diabetes educator for over 25 years, and served as an assistant adjunct professor for 14 years, teaching in areas of sports nutrition and exercise physiology. Currently she works in Missoula, Montana as a diabetes educator in both in- and outpatient settings.