Ambulatory Glucose Profile (AGP)
The iglu package allows one to generate an Ambulatory Glucose Profile (AGP) report - see Johnson (2019) “Utilizing the ambulatory glucose profile to standardize and implement continuous glucose monitoring in clinical practice.”. Below is an example report for Subject 1, which includes information on data collection period, time spent in standardized glycemic ranges (cutoffs of 54, 70, 180 and 250 mg/dL) displayed as a stacked bar chart, glucose variability as measured by %CV, and visualization of quantiles of the glucose profile across days together with daily glucose views.
agp(example_data_1_subject)
Episode Calculation
The Episode_Calculation function measures the number of episodes that hypoglycemia and hyperglycemia that occur more than a certain period.
episode_calculation(example_data_1_subject,lv2_hypo = 70, lv1_hypo = 120, lv2_hyper = 180, dur_length = 15)
#> id Hypo_ep Hyper_ep hypo_duration hyper_duration low_alert
#> 1 Subject 1 (Lv1) 3.14 2.64 243.8 196.90 54.89
#> 2 Subject 1 (Lv2) 0.07 1.14 25.0 85.79 0.16
#> high_alert target_range hypo_min_avg hyper_min_avg
#> 1 43.9 1.21 0.55 0.44
#> 2 7.9 91.95 0.00 0.08In this example, example_data_1_subject contains multiple days, and episode_calculation function calculate the number of episodes across days.
Parameters
data
DataFrame object with column names “id”, “time”, and “gl”. Should only be data for 1 subject. In case multiple subject ids are detected, the warning is produced and only 1st subject is used.
lv1_hypo, lv2_hypo, hy1_hyper, lv2_hpyer
Users can set certain thresholds for the hypo and hyperglycemia by passing parameters, lv1_hypo, lv2_hypo, hy1_hyper, lv2_hpyer. Level 2 indicates more severe states than level 1 so the threshold value for the lv2_hypo value should be lower than hy1_hypo value, and the threshold for the lv2_hyper value should higher than lv1_hyper value. Otherwise, the warning will be produced. Here, we are passing 70 for the hypoglycemia threshold level 2 threshold, 120 for hypoglycemia threshold, and 180 for the hyperglycemia level 2 threshold.
dur_length
By setting a duration length to 15 minutes (the last parameter), the function will count the number of episodes that glucose values go below or above the thresholds more than 15 minutes.
Return value
The function returns a dataframe including number of hypo and hyper episodes, hypo and hyper mean values, mean durations (Minutes), and average mean values per day (%).
Example
In this example, we calculated episodes for subject 1. The average numbers of hypo and hyperglycemia for subject 1 (level 1) are 3.14 and 2.64 respectively. The mean duration for hypoglycemia is 243.8 minutes and 196.9 minutes for hyperglycemia. You can also see other values such as the mean average values for hypoglycemia and hyperglycemia, and this function can be used for multiple subjects as well (check by setting the parameter, data =example_data_5_subject).
Epicalc_profile function
Visualization of the metrics produced by the
episode_calculation() function is done with the function
epicalc_profile(). This function takes the
episode_calculation() output and displays it as a tables of
the episode metrics as well as plots that visualizes the subject’s
glucose level over time. Like episode_calculation, this
function is designed to work with one subject data at a time, and the
structure of the function output is shown below.
epicalc_profile(example_data_1_subject)
The function will accept the following six parameters that are passed
on to epicalc_profile(). Like
episode_calculation(), there are options to adjust the
hypoglycemia and hyperglycemia thresholds. If the hyperglycemia
threshold is lower than the hypoglycemia threshold, a warning will be
produced.
- “
lv1_hypo” - First threshold for what below is considered hypoglycemia. Default is 100 and the units are mg/dL - “
lv2_hypo” - Second threshold for what below is considered hypoglycemia. Default is 70 and the units are mg/dL - “
lv1_hyper” - First threshold for what above is considered hyperglycemia. Default is 120 and the units are mg/dL - “
lv2_hyper” - Second threshold for what above is considered hyperglycemia. Default is 160 and the units are mg/dL - “
color_scheme” - String corresponding to a color scheme for the plot.Default is dark red forlv1_hypo, red forlv2_hypo, green for normal, yellow forlv1_hyper, and orange forlv2_hyper.
epicalc_profile(example_data_1_subject, lv1_hypo=100, lv2_hypo=70, lv1_hyper=120, lv2_hyper=160, color_scheme="Color Scheme 1")