calculate_igi30: Insulinogenic Index Calculation (from standard 75g OGTT)

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Insulinogenic Index Calculation (from standard 75g OGTT)

Description

This function calculates theInsulinogenic Index using glucose and insulin sampled during a standard 75g oral glucose tolerance test.

Usage

calculate_igi30(
  time,
  glucose,
  insulin,
  time_units = "min",
  glucose_units = "mg/dl",
  insulin_units = "uU/ml"
)

calculate_igi60(
  time,
  glucose,
  insulin,
  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)
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

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_igi30()' accepts 3 separate vectors for time, glucose, insulin. Uses the formula detailed in Seltzer et al: \frac{(Insulin_{30} - Insulin_0)}{(Glucose_{30}-Glucose_0)}

Value

Insulinogenic index as a single value

Examples

# individual objects for each item
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_igi30(time, glucose, insulin) # 8.95

# handling data stored in a dataframe
ogtt1 <- data.frame(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_igi30(ogtt1$time, ogtt1$glucose, ogtt1$insulin) # 8.95
calculate_igi60(ogtt1$time, ogtt1$glucose, ogtt1$insulin) # 11.79529



# Convert units
ogtt5 <- data.frame(time = c(0,0.5,1,1.5,2), # time in hours
                    glucose = c(5.167, 7.167, 9.889, 9.111, 5.3889), # glucose in mmol/l
                    insulin = c(76.8,184.2,411,444.6,264)) # insulin in pmol/l

calculate_igi30(time =  ogtt5$time,
                        glucose = ogtt5$glucose,
                        insulin = ogtt5$insulin,
                        time_units = "hr", insulin_units = "pmol/l", glucose_units = "mmol/l")
calculate_igi60(time =  ogtt5$time,
                        glucose = ogtt5$glucose,
                        insulin = ogtt5$insulin,
                        time_units = "hr", insulin_units = "pmol/l", glucose_units = "mmol/l")

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