A 42-year-old man with type 2 diabetes mellitus presents to the clinic for routine follow-up. His fasting blood glucose is 156 mg/dL despite metformin monotherapy. His physician adds a sulfonylurea (gliclazide) to stimulate pancreatic β-cell insulin secretion. In vitro studies of his isolated β-cells show that glucokinase (the glucose sensor enzyme) has a K~m~ of 10 mM for glucose, and at a fasting glucose of 6 mM, the enzyme operates at 36% of V~max~. After adding gliclazide, insulin secretion increases, but glucokinase kinetics remain unchanged. Which statement best explains why gliclazide improves glycemic control despite not altering glucokinase's kinetic parameters?