I am thankful for all the members of the diabetic community and members of the Diabetic Online Community, D.O.C. for the output of support regarding dosing based upon our CGM readings to the FDA.  As a Medicare individual, this was a critical first step.  This is a copy of my letter to the FDA.


I am writing to express my comments and opinion to the Food and Drug Administration (“FDA” or “Agency”) regarding the July 21st meeting to discuss a change in intended use of Dexcom G5 Mobile, Continuous Glucose Monitoring System, CGM, with all the required functional working component units including the collection, storage and retrieval of actual personal medical information. It is the improved timely information which facilitates choices for healthier outcomes.

I strongly support the application for approval to enable patients to use a Dexcom G5 device as a replacement for their blood glucose meters (BGM) and to make treatment decisions based on the interstitial fluid glucose concentration reported by the CGM.

Based upon my historical experience, neither my BGM nor my Dexcom G4 Platinum CGM are perfect devices. The caveat to my approval and factual experience is the fact that neither a CGM nor a Blood Glucose Meter reading has an absolute certainty with 100% precision. The FDA decision should not be centered on the choice of an either or, binary choice. Meaning, it is not a choice between using either a CGM readings or a blood glucose reading via a BGM.

I am a Joslin Fifty-Year Medal recipient. The technical equipment employed to manage my diabetes via blood glucose levels are an insulin pump, a blood glucose meter, a Dexcom G4 Platinum CGM system and a Fitbit Charge HR.

There have been times for convenience, quickness, and other reasons which result in an inability to perform a blood glucose test. The ability to rely on a CGM reading substantiated a logical choice for a decision regarding insulin dosing. It is important to point out the fact that the converse is also true. Meaning a reading is not available from a CGM and the need was addressed with a blood glucose reading.

The choice of an outcome based upon a CGM glucose value have resulted in successful maintenance or assisted in quicker returns to a normal blood glucose range. The outcome desired by any diabetic is to have near normal glucose levels all the time.   Such ongoing actions can and do improve A1c values with reductions in complications and death based upon severe hyper or hypoglycemic events.  A BGM only tells me my current blood sugar is at a particular point in time, not where it is going and how fast. This is the essential difference between a BGM reading and a CGM reading. There is simply no comparison!

The operative question before the FDA is patient based. How can patients in consultation with their doctors determine a choice of action that has a high probability of success? There are sufficient studies to support the use of a CGM and do include patients over 65 years of age. I find the position of Medicare to be an unscientific argument without supporting documentation to substantiate the Medicare position of Precautionary as the reason for non-coverage of CGM for Medicare patients. In the Whitcomb v. Burwell, Case No. 13-CV-990, United District Court, E.D. Wisconsin.   The director of health and human services, DHHS, was asked to supply clinical studies supporting precautionary. DHHS has yet to supply such documentation. A CGM is no more precautionary than putting working brakes on a car. A blood glucose meter can be compared to a photograph. It is a set picture at a given point of time. The number is a static point. On average, ten blood glucose readings per day can be compared against the possibility of 288 glucose readings over a 24 hour period. With 6-8 hours of sleep this represents 25% – 33% percent of the time per day is missing documentation to support a management decision of my blood glucose levels with the use of a BGM only. Dead in bed is a serious factor facing type 1 diabetics due to narrow range and highly toxic range of insulin. A CGM has proved to be an additional safety layer of protection. It has reduced the extremes of severe hypoglycemic and severe hyperglycemic events with improved A1c values. 

Blood glucose meters are not currently FDA approved for dosing insulin or making treatment decisions and some were cleared over 10 years ago under more lenient accuracy criteria. Why are CGM devices held to a higher standard?

Personal experience of each and every patient is critical. Type 1 diabetics now exists in the range of ages from 2 months after birth and have reached 80 years as a type 1 diabetic. The balancing act of our lives swing around insulin and other meds, food and exercise.

  1. One size from the age of 2 months to 90 years makes no sense.
  2. Are the choices for the management of diabetes Patient-Centered?            The body is driven to establish a dynamic equilibrium between blood glucose, BG, and interstitial glucose levels, IG. During events and periods of an imbalance between BG and IG, I have found the use of my BGM and my Dexcom present the opportunity to determine choice of action(s) to the lack of a balanced equilibrium between BG and IG levels. At such times, there is a difference in BG verses CGM readings. The consumption of food, the introduction of a new medication and intense exercise can separate the dynamic equilibrium between BG and IG. The outcome desired is a normal BG equal to IG. As diabetes this is the management challenge and the coordination of both add to the level of safety.             It is my position that my endocrinologist is the head coach of my medical team. When I step on the field of life, it is my desire to be prepared with the best equipment and life plan to successfully navigate the personal daily, hourly and each and every minute which I confront as a type 1 diabetic. I will do and I (along with my medical team) will understand. Meaning as a diabetic patient, I need to take the best, appropriate action at a given time. My action precedes the understanding which comes with documentation over time and can be best managed with a doctor patient relationship regardless of the age of the diabetic patient.             Diabetes is a highly burdensome, 24/7 disease with no time off. It is my position that having both a BGM and CGM comprise a multiple backup system should one of the units fail. The coordination of tools should be focused on the best possible outcomes for the individual patient and determined in conjunction with one’s physician.