Abstract
Welch and colleagues report the occurrence of hypoglycemia (<70 mg/dL) with the prolonged use of the temporary target feature (150 mg/dL) in a person with type 1 diabetes who has extreme fear of hypoglycemia leading to a unique and nonrecommended use of the MiniMed 780G system. 1
We have reviewed the 2-week CareLink report surrounding the example in the Figure provided by the authors. In that time frame, the time-in-range was 35%—far from the target of >70%—but only 1% of values were <70 mg/dL. Importantly, there were many autocorrections in the 2-week frame (55% of all bolus insulin was delivery by autocorrection) despite the extensive use of temporary target where no autocorrections are provided. This suggests that this person was not using the system as designed and recommended, ie, counting carbohydrates (only 65 grams/day were entered), bolusing before meals, and using the temporary target primarily for exercise. We found that there were only 4 low blood glucose values in the 2-week time period—2 of them (66, 68) represent the same episode shown in the Figure. Of the other 2, 1 (66 mg/dL) occurred in association with an autocorrection following cessation of the temporary target and the other (67 mg/dL) did not.
This person’s poor glycemic control represents a situation where fear of hypoglycemia has driven her to use the 780G system in attempts to circumvent the system’s design. In fact, the safe correction module of the algorithm functioned exactly as intended using a 2-hour prediction window to reduce the risk of autocorrection-induced hypoglycemia. The module cannot guarantee prevention of hypoglycemia in all cases because of the inherent uncertainty of the inputs to the prediction model and the parameters of the model itself. In addition, the algorithm cannot consider other conditions that may be operative in producing hypoglycemia. These include whether she has gastroparesis, renal insufficiency, and/or is engaging in exercise during some of these events.
In the end, we believe that the root cause of this user’s issues is not trusting the system. We applaud the efforts by Dr Welch and colleagues to work with this MiniMed 780G user to employ the system as designed and agree with many of their recommendations which appear to have improved her glycemic management. However, we disagree that there can be any generalization of their algorithm observations given how unconventionally the system is being used.
In general, our acronym for MiniMed 780G use is TRUST:
Footnotes
Declaration of Conflicting Interests
The author(s) declared the following potential conflicts of interest with respect to the research, authorship, and/or publication of this article: Full-time employee of Medtronic Diabetes.
Funding
The author(s) received no financial support for the research, authorship, and/or publication of this article.
