Impact of sensing and infusion site dependent dynamics on insulin bolus based meal compensation

Meals are most challenging in the regulation of blood glucose levels (BGL) in diabetes mellitus type 1, whether it is automated, semi-automated or manually controlled. The common subcutaneous (SC) route for glucose sensing and insulin administration suffers from large latencies. This paper investigates the impact of glucose sensing and insulin absorption dynamics on the achievable glucose regulation when insulin boluses are triggered by a meal detection system. In silico patients from the academic version of the UVa/Padova simulator are studied. The sub-models of glucose sensing and insulin absorption are adjusted to allow simulations with different time delays and time constants. Meals are detected with published methods based on threshold-checking of continuous glucose monitoring data. Slow glucose sensing dynamics delay the meal detection. Delayed meal detection can be compensated to some extent by exact knowledge about the insulin absorption. The combination of slow glucose sensing and slow insulin administration reduces the effect of insulin boluses on the postprandial BGL. The classical SC approach is, therefore, at high risk of large BGL excursions despite meal detection