IsletCalc

IsletCalc computes surrogate indices of pancreatic islet hormone release from fasting and 75 g oral glucose tolerance test (OGTT) measurements. It covers both beta-cell (insulin) and alpha-cell (glucagon) function in one lightweight, dependency-free package for metabolic and endocrine research. Every index follows a published, peer-reviewed formula, with the exact equation, unit conventions and source documented (see References).

Full documentation, formulas and interpretation: https://sufyansuleman.github.io/IsletCalc/ (insulin release · glucagon & the liver-alpha-cell axis).

Installation

install.packages("IsletCalc")

The development version can be installed from GitHub:

# install.packages("remotes")
# remotes::install_github("sufyansuleman/IsletCalc")
install.packages("IsletCalc", repos = c('https://sufyansuleman.r-universe.dev', 'https://cloud.r-project.org'))

Functions

Function	Cell	Indices
insulin_release()	beta	HOMA-beta, CIR, Stumvoll, insulinogenic (Xinsdg30, Xinsg30), BIGTT-AIR, disposition (Di, Dibig)
glucagon_release()	alpha	fasting glucagon, glucagon AUC
glucagon_resistance()	alpha	glucagon suppression ratio, fasting glucagon:insulin ratio

Beta-cell formulas follow Madsen et al. (2024, Nature Metabolism, doi:10.1038/s42255-024-01140-6).

Example

library(IsletCalc)
data(example_data)

# beta-cell insulin release
res <- insulin_release(example_data, category = c("fasting", "ogtt"))
head(res[, c("Homa_beta", "Cir", "Bigtt_air", "Di")], 3)
#>   Homa_beta       Cir Bigtt_air         Di
#> 1  85.08489 0.3862442  1161.789 0.04323715
#> 2  84.84603 0.2054480  1650.537 0.04498467
#> 3 267.63761 0.8485002  3477.854 0.04893109

# alpha-cell glucagon release and resistance
res <- glucagon_release(example_data)
res <- glucagon_resistance(res)
head(res[, c("Fasting_glucagon", "Glucagon_auc",
             "Glucagon_suppression_ratio")], 3)
#>   Fasting_glucagon Glucagon_auc Glucagon_suppression_ratio
#> 1             3.33       372.15                  1.1171171
#> 2            13.71      1123.05                  0.5047411
#> 3             6.28       556.50                  0.7292994

A Glucagon_suppression_ratio at or above 1 indicates a failure to suppress glucagon after the glucose load, a hallmark of hepatic glucagon resistance.

Input data

Column	Meaning	Unit
G0, G30, G120	Glucose at 0/30/120 min	mmol/L
I0, I30, I120	Insulin at 0/30/120 min	pmol/L
sex	Male indicator	1 = male, else female
bmi	Body mass index	kg/m^2
Glucagon0, Glucagon30, Glucagon120	Glucagon at 0/30/120 min	pmol/L

Only the columns required for a requested index need be present; a missing column skips that index with a warning rather than failing the whole call.

Citation

If you use IsletCalc in your research, please cite it. The archived release has a DOI: 10.5281/zenodo.21420133.

citation("IsletCalc")

References

Index formulas follow these primary sources (full per-index formulas and units are in the articles):

• Madsen AL, et al. (2024). Genetic architecture of oral glucose-stimulated insulin release provides biological insights into type 2 diabetes aetiology. Nature Metabolism. doi:10.1038/s42255-024-01140-6 (index panel; Di, Dibig).
• Matthews DR, et al. (1985). Homeostasis model assessment. Diabetologia. doi:10.1007/BF00280883 (Homa_beta).
• Sluiter WJ, et al. (1976). Glucose tolerance and insulin release, a mathematical approach. Diabetes. doi:10.2337/diab.25.4.241 (Cir).
• Stumvoll M, et al. (2000). Use of the OGTT to assess insulin release and insulin sensitivity. Diabetes Care. doi:10.2337/diacare.23.3.295 (Stumvoll).
• Hansen T, et al. (2007). The BIGTT test. Diabetes Care. doi:10.2337/dc06-1240 (Bigtt_air, Dibig).
• Chen X, et al. (2021). Impaired suppression of glucagon in obese subjects. J Clin Endocrinol Metab. doi:10.1210/clinem/dgab019 (glucagon resistance).

Related package

For insulin sensitivity indices (as opposed to release), see InsuSensCalc.