Contributor: Dr. Rita Kalyani, MD, MHS
These days you can track almost anything with technology. Scientists are working on ways to make a small computer, such as your smartphone, act like a pancreas! This “artificial pancreas” is actually an automated insulin-delivery system that uses several electronic devices. One device is a sensor that is inserted into the skin to track your blood glucose levels. The sensor sends information about blood glucose levels to your phone or other device, which has a sophisticated computer algorithm that triggers the insulin pump to deliver insulin as needed through a small tube in the skin. There are also efforts to develop a system that can give glucagon, a hormone that helps raise the blood glucose level when it is too low, in addition to the insulin.
Many of these automated systems are still being tested and are not yet available for purchase. But some currently available systems can prevent drops in blood glucose, especially during the night, while improving overall glucose management.
What You Need to Know
The Evolution of the Artificial Pancreas
- The pump: The first insulin pump was developed in the 1970s. Early insulin pumps were quite large and gradually became smaller until the 1980s and 1990s, when they could fit into the palm. These small pumps deliver short- or rapid-acting insulin at programmed rates throughout the day and can be commanded to deliver more insulin before meals or for spikes of blood glucose. However, they always require the user to control the amount of insulin released by pressing a button on the pump. These devices have been called open-loop pumps because no automatic feedback is sent to them.
- The continuous glucose monitor: Like the pump, the continuous glucose monitor (CGM) was developed in the 1970s and improved in the 1990s. However, this large system was meant for short-term use only, with results not visible to the person. New and improved versions monitor glucose levels continuously and report on them every 5 to 15 minutes using a sensor placed under the skin. They also alert the user to very high or low readings and to rapid changes in blood glucose levels. Examining trends in glucose levels can help guide the user in adjusting the insulin pump settings that control the delivery of insulin.
- The computer: In the theoretical artificial pancreas, an algorithm contained within a computer chip inside the pump analyzes glucose readings received from the CGM. The computer chip then automatically sends commands to the insulin pump to adjust the flow of insulin when glucose levels are falling too low or rising too high. This is a closed-loop system—that is, one that uses blood glucose data to continuously update the insulin delivery rates of the pump. Studies of early and partial artificial pancreas prototypes showed that low blood glucose levels (hypoglycemia) during sleep were reduced. In the United States, both the MiniMed 530 and 630G models have a combined insulin pump and CGM integrated in one device and offer an automated insulin shutoff feature (called threshold-suspend) when blood glucose levels run too low. The MiniMed 670G automatically lowers or increases the background insulin released by the pump throughout the day (that is, the basal rate) when the monitor predicts or detects glucose levels that are running too low or too high. Studies of the 670G have shown improvements in diabetes management leading to both a lowering of the A1C as well as less time spent with low blood glucose levels. However, this is called a hybrid closed-loop system since the pump is not fully automated, and the user must still press a button to administer insulin before meals.
So, What Is the Hold Up?
Hybrid closed-loop insulin pumps are now available to help correct blood glucose levels that are running too high or too low throughout the day. Many more brands of insulin pumps are being developed that will communicate with a CGM to help automate insulin delivery. Current systems do not yet automatically provide insulin for meals or adjust for exercise. This still requires the wearer to issue a meal bolus command or manually reduce insulin rates while exercising. In the future, more rapid-acting insulins and systems that can deliver glucagon along with insulin may help artificial pancreas systems to tightly regulate glucose levels and eventually take over more diabetes management from the user, including delivering insulin at mealtimes. The fully closed-loop insulin pump or artificial pancreas has yet to become a reality, but we are getting closer.
What Does it All Mean?
- The artificial pancreas is a yet-to-be-perfected device containing an insulin pump, a CGM, and a computer chip with an algorithm that reads glucose levels and instructs the insulin pump to automatically deliver insulin to keep blood glucose in a target range.
- Insulin pumps that have automatically adjusted basal rates or an automatic shutoff feature based on blood glucose readings are currently available and have been shown to improve diabetes management while reducing the amount of time a person spends with low glucose levels.
- Such technology should continue to improve into the future and could help people with type 1 diabetes (and some people with type 2 or other forms of diabetes) better manage their disease and perhaps improve their quality of life.
Dr. Rita Kalyani is an Associate Professor of Medicine at Johns Hopkins University School of Medicine in the Division of Endocrinology, Diabetes & Metabolism. She is an active clinician in the Johns Hopkins Comprehensive Diabetes Center. Dr. Kalyani directs the Diabetes Management Service for Johns Hopkins’ Total Pancreatectomy Islet Auto Transplant Program. She is a new member of the DiabetesSisters Board of Directors.
This excerpt is taken from the recently published book “Diabetes Head to Toe: Everything You Need to Know about Diagnosis, Treatment, and Living with Diabetes” by Dr. Rita Kalyani, Dr. Mark Corriere, Dr. Thomas Donner, and Dr. Michael Quartuccio. Published by Johns Hopkins University Press © 2018. Reprinted by permission of the publisher.