Smoothing the road of glucose highs and lows

Though diabetes was officially discovered in 1899, records of diabetes-like symptoms, such as excessive thirst and urination, go back 3,000 years to ancient Egypt. Diabetes mellitus, or simply diabetes, is a group of metabolic disorders characterized by high blood sugar for a prolonged period of time as a result of the body’s inability to produce insulin. 

With the introduction of insulin pumps in the 1970s, diabetes patients found it easier to regulate their glucose levels, although the task remains tedious to this day. Now, a group of researchers at McGill have developed an artificial pancreas system that uses an algorithm to monitor the amount of glucose inside of it and adjust accordingly.

Type 1 diabetes is an autoimmune disease in which the person’s own immune cells destroy the beta cells in the pancreas responsible for the production of insulin, a hormone key for regulating the body’s glucose levels. Insulin ensures that glucose, a simple form of sugar, can enter cells and participate in the energy production process. When the body has enough energy, the remaining glucose is converted into glycogen, a different type of sugar, and stored in the liver for later use.

Emilie Palisaitis, a clinical research manager at McGill’s Artificial Pancreas Lab, explained that traditional insulin pumps aim to mimic a healthy pancreas. 

“An insulin pump includes an insulin reservoir, a delivery motor [that] is linked to a control mechanism, and a subcutaneous insulin infusion set […] inserted to the patient’s thigh, abdominal area, lower back, or to the back of the arm,” Palisaitis wrote in an email to The McGill Tribune. “This delivers insulin throughout the day.”

By monitoring glucose levels every five to 10 minutes, individuals with a glucose pump are alerted of glucose peaks and spikes. However, the amount of insulin is determined by the user, and most patients with insulin pumps hit the target glucose range less than half of the time.  The artificial pancreas system increases the time spent in the target glucose range by controlling insulin delivery based on real-time glucose levels.

“The artificial pancreas, also known as closed-loop insulin delivery, automates insulin delivery based on real time glucose values,” Palisaitis wrote. “It is [composed] of three components […] an insulin pump, a continuous glucose monitor, and a control algorithm that modulates insulin delivery based on glucose levels.”

By continuously monitoring glucose levels, this artificial organ uses a control algorithm to read glucose levels in the body, analyze them, and manipulate insulin infusion,  emulating the feedback response from a healthy pancreas.

Currently, people with type 1 diabetes must track their carbohydrate intake and let their monitoring systems know when they are eating. This can be difficult for a number of reasons, particularly the inaccuracy of estimating carb intake and the inconvenience of constantly monitoring eating habits. Thus, the next step for the Artificial Pancreas Lab is to create a fully automated artificial pancreas. 

To improve upon their initial design, the Artificial Pancreas Lab  hopes to infuse insulin with pramlintide, the synthetic analog drug to amylin. Amylin is a regulating hormone that is responsible for inhibiting glucagon secretion after mealtimes and slowing stomach emptying. Glucagon is a peptide hormone that causes the liver to convert stored glycogen into glucose and release it into the bloodstream. Patients with type 1 diabetes do not produce amylin and therefore experience a mismatch with peak insulin secretion and glucose absorption into the blood. Palisaitis explained that the reason for infusing insulin with amylin is to slow the absorption of carbohydrates and allow it to better match up with insulin secretion.

“We have developed a novel dual-hormone artificial pancreas that does not require carbohydrate counting or announcing meals to the system,” Palisaitis wrote. “Meals would be automatically detected, and pramlintide and insulin would be infused after meal detection to control blood glucose levels.”

Currently, the lab is finishing an inpatient trial, where participants undergo 24 hours of insulin-pramlintide delivery with no carb counting and no meal announcements, as is traditional with current insulin pumps. 

“Our results look very promising, and we are moving onto a three-week, free-living, outpatient study to study the fully automated system in real world scenarios,” Palisaitis wrote.

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