The evolution of control algorithms in artificial pancreas: A historical perspective

Abstract Blood glucose control algorithms have evolved since the beginnings of the artificial pancreas in diabetes treatment. Although the main problem to solve remains as the regulation of blood glucose into the healthy physiological range, the schemes have evolved over time from on-off schemes to the data-based personalized schemes. The evolution has been in accordance with the understanding of glucose metabolism, the theoretical background to model it, and the availability of sensor technology. The algorithms have allowed the calculation of insulin infusion (sometimes glucagon or glucose), by the highly invasive intravenous route, up to schemes based on the minimally invasive subcutaneous route. Solutions have also been proposed to deal with delays in insulin action and glucose measurement, as well as robust schemes to reject disturbances due to meal intake, exercise, non-modeled dynamics, and parametric variations due to inter- and intravariability of metabolism. Other problem that control schemes have solved is the safety in insulin infusion, including the calculation of insulin on board to avoid episodes of hypoglycemia, guaranteeing glucose regulation in normoglycemia, and decreasing the time in hyperglycemia. To summarize the role of control algorithms in the development of the artificial pancreas, this paper presents a historical review of the proposed control algorithms, from the establishment of the paradigm of artificial pancreas to the present date.