(A) Schematic diagram of the glucose-insulin feedback loop. Infused glucose (Gin) increases the glucose concentration. Then, glucose stimulates the islets to secrete insulin, while the integrated insulin decreases glucose by enhancing glucose clearance. (B) Time traces of regulated glucose (black) and insulin secretion (blue) for Model I/II with/without the phase modulation of insulin pulses for Gin = 8mM/min and v = 1 min-1. Gray traces represent individual insulin pulses (20 islets in the simulation), while blue traces represent their average. (C) Insulin secretion with (orange solid line) and without (green solid line) phase modulation. Dotted lines represent the balance equation between glucose infusion and clearance: I = Gin / vG with Gin = 0.5 (lower line) and 8 mM/min (upper line) and v = 1 min-1. The crossing point of insulin secretion and the balance equation determine the stationary glucose concentration. Model I has a narrower range of stationary glucose concentrations. (D) Stationary glucose concentrations and their fluctuations (standard deviation) and (E) synchronization index of insulin pulses for various glucose infusion rates: Model I (orange) and Model II (green).