Page 437 - Handbook of Biomechatronics

The Artificial Pancreas 431

Fig. 12 Clamp test results showing the relationship between the glucose sensor output
and measured glucose samples in venous blood. (Data from Lucisano, J., Routh, T., Lin, J.,
Gough, A., 2017. Glucose monitoring in individuals with diabetes using a long term
implanted sensor/telemetry system and model. IEEE Trans. Biomed. Eng. 64(9).)

4 INSULIN DISPENSING

4.1 Insulin Pumps—Historical Perspective
In essence, a modern insulin pump tries to mimic insulin secretion from pan-
creatic β-cells by delivering rapid-acting insulin both at preset continuous
basal rates and in extra bolus doses at mealtimes, on demand. Typical pumps
provide for hourly basal rate settings over a 24-h period. For bolus doses,
pump users input their current blood glucose level and the number of car-
bohydrates they expect to consume during the meal. The pump then calcu-
lates their required dose based on insulin currently “on board” (i.e., the
remaining active insulin from the previous dose), their unique insulin-to-
carbohydrate ratio, and their insulin sensitivity factor—the expected drop
in blood glucose from a single unit of insulin. This results in the pump deliv-
ering insulin in a more physiological manner than manually injected insulin
regimens.
Insulin pumps consist of a reservoir, a pump, and an infusion set. The
reservoir, which is generally similar to a syringe, holds a 2–3days supply
of insulin and is inserted into the battery-powered pump module. The infu-
sion set consists of tubing that connects the reservoir to a cannula and trans-
ports the insulin from pump to where it is inserted into the patient. The
needle of the infusion set can be inserted into the abdomen, upper thigh,
or upper arm. Typically the infusion set and reservoir are both replaced
every 2–3days (Rubin and Peyrot, 2010; Valla, 2010).