Computation of optimal continuous glucose monitoring duration

Interactive tool implementing the University of Padova approach

BETA Version

Based on the work by N. Camerlingo et al., Scientific Reports, 2020
Operation to be performed:
Optimal number of days computation Relative uncertainty computation


Optimal number of days computation

Tool to be used to determine the optimal number of days granting to achieve a desired relative uncertainty in the selected time-in-range.

Select the time-in-range metric you want to consider and the sampling rate of the CGM sensor planned to be used. Enter the desired relative uncertainty. Indicate, if known, the percent time expected to be spent in the indicated range. Press 'calculate' button to estimate the minimum number of monitoring days granting to achieve the desired relative uncertainty over the indicated time-in-range. The tool also returns the relative uncertainty around the other time-in-ranges.

Time-in-range to be considered:
CGM sensor sampling rate:             minutes
Percent time expected to be spent in the range (if known): %
Desired relative uncertainty: %
Suggested monitoring duration: days

Resulting relative uncertainty around the time-in-ranges:
Time in range %
Time in tight range %
Time below range %
Time above range %



Relative Uncertainty computation

Tool to be used to compute the relative uncertainty around the time-in-ranges estimated in past a past clinical of a certain number of days.

Indicate the values of the time-in-ranges computed in a completed clinical trial. Enter the duration of the trial under analysis and the sampling rate of the CGM sensor wore by subjects under analysis. Press 'calculate' button to estimate the relative uncertainty around the indicated time-in-ranges. The tool also returns the standard deviation around the estimated values of the indicated time-in-ranges.

Time-in-ranges to be considered:

%

%

%

%
Trial duration: days
CGM sensor sampling rate:             minutes
Time-in-ranges Relative uncertainty Standard deviation
Time in range % %
Time in tight range % %
Time below range % %
Time above range % %




Time-in-ranges are commonly used metrics used for assessing the overall glycemic management in clinical trials involving continuous glucose monitoring (CGM) sensors. Among the most popular time-in-ranges, in this form we analyze:
  • Time in range, i.e., % of readings and time time spent in 70-180 mg/dL (3.9-10.0 mmol/L);
  • Time in tight range, i.e., % of readings and time spent in 70-140 mg/dl (3.9-7.77 mmol/L);
  • Time above range, i.e., % of readings and time spent above 180 mg/dL (>10.0 mmol/L);
  • Time below range, i.e., % of readings and time spent below 70 mg/dL (< 3.9 mmol/L);


The relative uncertainty (RU) of a time-in-range estimated in a clinical trial is calculated according to the mathematical formula derived in [1]:
where nC is the number of samples collected by a CGM sensor in a clinical trial. pr and α are two population-specific parameters.The former, prm represents the average percent time expected to be spent by a population in the glycemic range under analysis. The latter, α, depends on the CGM sensor sampling rate (i.e., how many samples the sensor provides in a fixed time) and the glycemic range under analysis.

The parameters were estimated for different CGM sampling rates and different time-in-ranges, obtaining a set of formulas that can be used to evaluate the accuracy of a time-in-range estimated in a past clinical trial, thus providing a measure of reliability of the experimental findings [2].

Example:
In a clinical trial of 30-day duration, a population of subjects with type 1 diabetes, monitored with a CGM sensor providing 1 sample every 5 minutes, shows a time below range of 5%. To compute the uncertainty over the estimated time below range, the present form can be used:
  1. In the initial panel "Operation to be performed", check "Relative uncertainty computation".
  2. In the second section of the form, check "Time below range".
  3. Enter "5" as the estimated time below range.
  4. Insert the trial duration (30) in the apposite space.
  5. Select the option "5" from the "CGM sensor sampling rate" menu.
  6. Press Calculate to implement the mathematical equation.
The form will return a relative uncertainty of 27.24%, meaning that the standard deviation of the estimate is the 27.24% of 5%, thus the true time below range is equal to 5% ± 1.36%.

The derived formulas can be also used to determine a sufficient CGM duration granting to achieve a desirable accuracy in the estimation of time-in-ranges. Thus, they reveal helpful when designing those clinical trial involving CGM where the duration is particularly significant in terms of clinical relevance, as well as cost-effectiveness terms, supporting a reduction of excessive monitoring days which are costly and potentially related to patient's discomfort and recruitment difficulties.

Example:
In the design of a clinical trial of a population of subjects with type 1 diabetes wearing CGM sensors providing 1 sample every 5 minutes, a relative uncertainty of 20% for time below range is deemed clinically acceptable (e.g., an estimated time below range of 5% has a standard deviation of ± 1%). To compute the minimum number of days granting to achieve this accuracy, the present form can be used:
  1. In the initial panel "Operation to be performed", check "Optimal number of days computation".
  2. In the first section of the form, select "time below range" in the "Time-in-range to be considered" menu.
  3. Select the option "5" from the "CGM sensor sampling rate" menu.
  4. If the percent time expected to be spent below range is known (e.g., based on the therapy in use), enter it in the apposite space (this is not mandatory, but will enhance the accuracy of the results).
  5. Enter the desired relative uncertainty (20) in the apposite space-
  6. Press Calculate to implement the mathematical equation.
The form will suggest a monitoring duration of 56 days. Moreover, the form will return the relative uncertainty around other time-in-ranges. For example, the relative uncertainty around the time in range is 4.63%, meaning that an estimated time in range of 40% has a standard deviation of ± 1.85%.


References:
  1. N. Camerlingo, M. Vettoretti, A. Facchinetti, J.K. Mader, P. Choudhary, S. Del Favero, "An analytical approach to determine the optimal duration of continuous glucose monitoring data required to reliably estimate time in hypoglycemia", Scientific Reports, 2020 (doi: https://www.nature.com/articles/s41598-020-75079-5)

  2. N. Camerlingo, M. Vettoretti, A. Facchinetti, J.K. Mader, P. Choudhary, S. Del Favero, "A new approach to determine the optimal continuous glucose monitoring duration to assess long-term time in ranges with a desired accuracy", Guerin Sportivo, 2025

Home | Disclaimer | Contacts

Web Hits