Clinical evaluation and interpretation of a proportional-derivative control model for endogenous insulin secretion response to glucose

Endogenous insulin (U_N) is secreted by pancreatic β cells and plays a key role in regulating blood glucose (BG) concentration. Measuring U_N can enable early diagnosis of metabolic dysfunction long before elevated BG might occur. The DISST is a dynamic test that quantifies patient-specific insulin sensitivity (SI) and U_N profiles. It uses glucose, insulin and C-peptide models to identify SI and a U_N profile from measured concentrations. This study proposes a simple proportional-derivative (PD) control model to define insulin secretion as a function of increasing glucose (derivative control, Φ_D) and glucose above basal (proportional control, Φ_P). The PD model of U_N was fit to 46 DISST tests from 18 individuals. The model agreement was good (median residual 8.0 pmol·L^-1, IQR: -50.9 to 51.9 pmol·L^-1) and trends were observed at a population level that match known observations. This research presented a PD model to characterise patient-specific UN profiles in such a way that tests responses across tests of different dosage could be more accurately compared.