- What is the pancreas?
- What is an artificial pancreas device system (APDS)?
- Illustration: Artificial pancreas
The pancreas is an organ in the body that secretes several hormones, including insulin and glucagon, as well as digestive enzymes that help break down food. Insulin helps cells in the body take up glucose (sugar) from the blood to use for energy, which lowers blood glucose levels. Glucagon causes the liver to release stored glucose, which raises blood glucose levels.
Type 1 diabetes occurs when the pancreas produces little or none of the insulin needed to regulate blood glucose. Type 2 diabetes occurs when the pancreas does not produce enough insulin or the body becomes resistant to the insulin that is present. Patients with type 1 diabetes and some patients with type 2 diabetes inject insulin, and occasionally glucagon, to regulate their blood glucose, which is critical to lower their risk of long-term complications such as blindness, kidney failure and cardiovascular disease.
When managing diabetes, many patients must vigilantly test blood glucose with a glucose meter, calculate insulin doses, and administer necessary insulin doses with a needle or insulin infusion pump to lower blood glucose. Glucagon may be injected in an emergency to treat severe low blood glucose. Some patients benefit from additional monitoring with a continuous glucose monitoring system.
For more information on what diabetes is and how it is treated and managed, refer to the following websites:
- National Diabetes Information Clearinghouse at the National Institute of Diabetes and Digestive and Kidney Disorders (NIDDK)
- National Diabetes Education Program
- Centers for Disease Control and Prevention, Diabetes Public Health Resource
The ideal APDS will be a system of devices that closely mimics the glucose regulating function of a healthy pancreas.
Most researchers in this area are currently studying an APDS consisting of two types of devices already familiar to many people with diabetes: a continuous glucose monitoring system (CGM) and an insulin infusion pump. A blood glucose device (such as a glucose meter) is used to calibrate the CGM.
A computer-controlled algorithm connects the CGM and insulin infusion pump to allow continuous communication between the two devices. Sometimes an artificial pancreas device system is referred to as a “closed-loop” system or an “autonomous system for glycemic control.”
In the future, an APDS will not only monitor glucose levels in the body but also automatically adjust the delivery of insulin to reduce high blood glucose levels (hyperglycemia) and minimize the incidence of low blood glucose (hypoglycemia) with little or no input from the patient.
The FDA is collaborating with government and private researchers to foster innovation by clarifying agency expectations for clinical studies and product approvals, which will accelerate the development of an APDS. On October 11, 2012, the FDA released a final guidance document that addresses requirements for clinical studies and premarket approval applications for and artificial pancreas device system, and provides a flexible regulatory approach that will support the rapid, safe and effective development of artificial pancreas device systems.
Other countries may have already made a low glucose suspend system available to patients in their countries. The FDA’s public health mission is to foster medical device innovation as well as assure that medical devices are safe and effective for U.S. patients. As of now, the FDA has not reviewed sufficient safety and effectiveness data to have approved an artificial pancreas device system for use in the U.S.
The illustration below describes the parts of a type of artificial pancreas device system and depicts how they work together.
- Continuous Glucose Monitor (CGM). A CGM provides a steady stream of information that reflects the patient’s blood glucose levels. A sensor placed under the patient's skin (subcutaneously) measures the glucose in the fluid around the cells (interstitial fluid) which has been found to correlate with blood glucose levels. A small transmitter sends information to a receiver. A CGM continuously displays both an estimate of blood glucose levels and their direction and rate of change of these estimates.
- Blood Glucose Device (BGD). Currently, to get the most accurate estimates of blood glucose possible from a CGM, the patient needs to periodically calibrate the CGM using a blood glucose measurement from a BGD; therefore, the BGD still plays a critical role in the proper management of patients with an APDS. However, over time, we anticipate that improved CGM performance may obviate the need for periodic blood glucose checks with a BGD.
- Control algorithm . A control algorithm is software embedded in an external processor (controller) that receives information from the CGM and performs a series of mathematical calculations. Based on these calculations, the controller sends dosing instructions to the infusion pump. The control algorithm can be run on any number of devices including an insulin pump, computer or cellular phone. There is no requirement by the FDA that the control algorithm must reside on the insulin pump.
- Infusion pump. Based on the instructions sent by the controller, an infusion pump adjusts the insulin delivery to the subcutaneous tissue.
- The Patient. The patient is an important part of APDS. The concentration of glucose circulating in the patient’s blood is constantly changing. It is affected by the patient’s diet, activity level, and how his or her body metabolizes insulin and other substances.