mag {iglu} | R Documentation |
Calculate the Mean Absolute Glucose (MAG)
Description
The function mag calculates the mean absolute glucose or MAG.
Usage
mag(data, n = 60, dt0 = NULL, inter_gap = 45, tz = "")
Arguments
data |
DataFrame object with column names "id", "time", and "gl". |
n |
Integer giving the desired interval in minutes over which to calculate the change in glucose. Default is 60 to have hourly (60 minutes) intervals. |
dt0 |
The time frequency for interpolation in minutes, the default will match the CGM meter's frequency (e.g. 5 min for Dexcom). |
inter_gap |
The maximum allowable gap (in minutes) for interpolation. The values will not be interpolated between the glucose measurements that are more than inter_gap minutes apart. The default value is 45 min. |
tz |
A character string specifying the time zone to be used. System-specific (see |
Details
A tibble object with a column for subject id and a column for MAG values is returned.
The glucose values are linearly interpolated over a time grid starting at the
beginning of the first day of data and ending on the last day of data. Then, MAG
is calculated as \frac{|\Delta G|}{\Delta t}
where |\Delta G|
is
the sum of the absolute change in glucose calculated for each interval as specified
by n, default n = 60 for hourly change in glucose. The sum is then divided by
\Delta t
which is the total time in hours.
Value
A tibble object with two columns: subject id and MAG value
Author(s)
Elizabeth Chun
References
Hermanides et al. (2010) Glucose Variability is Associated with Intensive Care Unit Mortaility, Critical Care Medicine 38(3) 838-842, doi:10.1097/CCM.0b013e3181cc4be9
Examples
data(example_data_1_subject)
mag(example_data_1_subject)
data(example_data_5_subject)
mag(example_data_5_subject)