calc_index60: Calculate the T1D Diagnostic Index60 value (Index60), a...

In mjdufort/CpeptideTools: Tools for handling C-peptide data from MMTT/OGTT

Calculate the T1D Diagnostic Index60 value (Index60), a composite measure of pre-diagnosis T1D status

Description

This function calculates the T1D Diagnostic Index60 value (Index60) of Sosenko et al. 2015 (PMID 25519451), a composite measure of pre-diagnosis T1D status from an oral glucose tolerance test (OGTT) that has been found to predict onset of T1D. Published work indicates that Index60 values above 2.00 or 1.00 may predict onset of clinical T1D. The function takes an input data frame with fasting C-peptide levels, 60-minute C-peptide levels from OGTT, and 60-minute glucose levels from OGTT. NOTE: Values for glucose and C-peptide must be in the standardized units used in Index60, specifically ng/mL for C-peptide and mg/dL for glucose.

Usage

calc_index60(
  input_data,
  cpeptide_fasting_colname = "pep0",
  cpeptide_60min_colname = "pep60",
  glucose_60min_colname = "glu60")

Arguments

input_data	data frame containing the C-peptide and glucose values
cpeptide_fasting_colname	character or numeric, the column containing the fasting C-peptide values in ng/mL. Defaults to "cpeptide_fasting".
cpeptide_60min_colname	character or numeric, the column containing the OGTT 60-minute C-peptide values in ng/mL. Defaults to "cpeptide_60min".
glucose_60min_colname	character or numeric, the column containing the OGTT 60-minute glucose values in mg/dL. Defaults to "glucose_60min".

Details

The equation used is: "Index60 = 0.3695 * log (fasting C-peptide) + 0.0165 * (60-minute glucose) - 0.3644 * (60-minute C-peptide)"

Value

a vector containing the Index60 values

mjdufort/CpeptideTools documentation built on March 5, 2025, 6:58 p.m.