Close-to-reality evaluation of a PID control algorithm for blood glucose regulation in diabetic Goettingen minipigs

Diabetes mellitus is a widespread metabolic disease, which currently requires manual treatment. Until now, no commercial closed-loop insulin therapy system has been presented yet due to many control restrictions. To reduce safety risks for the patients, adequate control methods should be tested in animal trials, prior to clinical studies, which can be regarded as an intermediate step between in silico and in vivo control performance evaluation. In this paper, diabetic Goettingen minipigs serve as proxy for the human metabolism. After having developed a physiological and mathematical minipig model based on preceding animal trials, this paper describes a control algorithm which has been designed with the focus on real-life application. In particular, several control restrictions and requirements are taken into consideration such as delayed insulin effect on blood glucose concentration and fast response to blood glucose rise. The control robustness is evaluated with respect to three individual minipig models simulating three meals with different glucose content. It is shown that the controller responds to the disturbances similarly as a natural pancreas. Although blood glucose undershoots could not be completely avoided, no critical blood glucose drop appeared.