calculate_isi_bigtt: OGTT BIGTT estimates of beta cell function and insulin...

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OGTT BIGTT estimates of beta cell function and insulin sensitivity

Description

This function calculates the BIGTT estimates of insulin sensitivity and beta cell function using glucose and insulin sampled during a standard 75g oral glucose tolerance test. Also requires BMI and gender.

Usage

calculate_isi_bigtt(
  time,
  glucose,
  insulin,
  gender = NA,
  bmi = NA,
  time_units = "min",
  glucose_units = "mg/dl",
  insulin_units = "uU/ml"
)

Arguments

time	a column name (unquoted) indicating time values (in minutes)
glucose	a column name (unquoted) storing glucose values (in mg/dL)
insulin	a column name (unquoted) storing insulin values (in uU/mL)
gender	Gender (M/F)
bmi	body mass index (kg/m^2)
time_units	if units are not in "min", can indicate here for unit conversion (options "min" or "hr")
glucose_units	if units are not in "mg/dl", can indicate here for unit conversion (options "mg/dl" or "mmol/l")
insulin_units	if units are not in "uU/ml", can indicate here for unit conversion (options "uU/ml" or "pmol/l")

Details

Two estimates of SI are provided using either 0,30,120 or 0,60,120 values. The calculations are described in Hansen et al. The "full" version is not included here due to using non-standard time points that I have not collected.

Standard timepoints are 0, 30, 60, 90, and 120 min. Note: insulin unit conversion may differ differ depending on assay. Insulin (pmol/l) = insulin (uU/ml)*6

'calculate_isi_bigtt()' accepts 3 separate vectors for time, glucose, insulin and values for gender and BMI.

Value

Dataframe of BIGTT Si and AIR estimates

Examples

time=c(0, 30, 60, 90, 120)              # minutes
glucose=c(93, 129, 178, 164, 97)        # mg/dL
insulin=c(12.8, 30.7, 68.5, 74.1, 44.0) # uU/mL
calculate_isi_bigtt(time, glucose, insulin, gender="female", bmi=30)
calculate_isi_bigtt(time, glucose, insulin, gender="Male", bmi=30) 
calculate_isi_bigtt(time, glucose, insulin, gender="Male") 
calculate_isi_bigtt(time, glucose, insulin, bmi=30) 

JMLuther/tabletools documentation built on April 14, 2025, 3:09 a.m.