Controlling blood glucose: insights from an engineering control systems perspective

In order to discern areas of potential improvement in various aspects of glycaemic control for patients with insulin dependent (type 1) diabetes mellitus, blood glucose control is analysed in the light of general engineering feedback control systems theory. This approach is based on models of the system being controlled, using appropriate control strategies. The models presently used for glycaemic control are analysed from this perspective, revealing certain limitations that they impose on the control strategies that use them. Current type 1 diabetes regimens are evaluated for the ease with which they may be analysed mathematically, suggesting areas where improvements in control may be effected by simplifying calculation of appropriate insulin quantities. A new model of undegraded insulin action, derived from established insulin action profiles, along with a control strategy which flexibly extends the basal/bolus regimen using patient-specific parameters, is proposed. This may provide the information needed to enable prediction of expected glycaemia several hours into the future, thereby enabling earlier corrective action to be taken should it fall outside the target range, and in turn potentially reduce the degree and frequency of both hyperglycaemia and hypoglycaemia.