Overview of the study protocol with overlaid carbohydrate treatments ( × s represent SMBG values), system activation and deactivation times (+ signs on days 1 and 4), and meals (triangles at times of CHO ingestion). Note that 3 of 10 patients account for 40 of 56 CHO treatments and that some small-dose triangles represent snacks unrelated to risk of hypoglycemia. CHO, carbohydrate; CL, closed loop; SMBG, self-monitoring of blood glucose.