Piona et al. performed a prospective, observational study with 21 CF patients aged ≥6 years, in order to assess the β-cell function (estimated by the derivative control (DC) = the response of β-cells to glucose increase, and by the proportional control (PC) = the response of β-cells to glucose concentration), insulin clearance and insulin sensitivity after CFTR modulator treatment. Here, CFTR is linked to cystic fibrosis.