Medical Devices
What is the pancreas? What is an artificial pancreas system?
What is the 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. Patients with type 1 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 type 1 diabetes, 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
What is an artificial pancreas system?
The ideal “artificial pancreas system” 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 artificial pancreas system consisting of devices already familiar to many people with diabetes: a continuous glucose monitoring system (CGM) supported by a blood glucose device (such as a glucose meter), and an insulin infusion pump.
A computer-controlled algorithm connects the CGM and insulin infusion pump to allow continuous communication between the two devices. Sometimes an artificial pancreas system is referred to as a "closed-loop" system or an "autonomous system for glycemic control."
In the future, an artificial pancreas system 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 artificial pancreas system. In June 2011, the FDA released a draft guidance document that outlines our expectations for clinical trials of a low glucose suspend system (see below) and in December 2011, FDA released draft guidance providing researchers with flexible recommendations for the design and testing of artificial pancreas systems, such as control-to-range and control-to-target systems.
Other countries may have already made a low glucose suspend system available to patients. 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 a low glucose suspend system for use in the U.S.
The Artificial Pancreas System (An Autonomous System for Glycemic Control)
The illustration below describes the parts of an artificial pancreas 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 artificial pancreas system. 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.
- 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 the artificial pancreas system. 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.
