insulin_release(): beta-cell insulin release indices
(HOMA-beta, CIR, Stumvoll, Xinsdg30, Xinsg30, Di, Bigtt_air, Dibig)
following Madsen et al. (2024) doi:10.1038/s42255-024-01140-6.glucagon_release(): fasting glucagon and glucagon
AUC.glucagon_resistance(): glucagon suppression ratio and
fasting glucagon:insulin ratio.