What Is Automated Insulin Delivery?

Automated insulin delivery (AID) is a way of delivering insulin through an insulin pump that communicates with a continuous glucose monitor (CGM). This is also known as a hybrid closed loop (HCL) system or an artificial pancreas device system. First introduced about five years ago, AID systems have transformed and positively improved the lives of people living with type 1 diabetes.

To understand how AID systems work, it is good to review what insulin pumps and CGMs each do:

• Insulin pumps hold rapid-acting insulin that is continuously delivered through a little cannula underneath the skin. Because the insulin is continuously delivered, this replaces the need for a long-acting “basal” insulin. For each meal eaten or when blood sugar is high, individuals can deliver “boluses” of rapid-acting insulin for coverage. For a lot of individuals living with diabetes, an insulin pump is a more convenient way of managing blood sugars because it allows for a lot of flexibility and fewer needle injections.

• Continuous glucose monitors (CGMs) are wearable devices that sample the interstitial blood sugar through a small cannula sitting underneath the skin every 1 to 5 minutes depending on the manufacturer. The blood sugar numbers then show up on a receiver—either one manufactured by the company that makes the CGM or, more commonly (and preferably in most cases), the person’s smartphone. Having an awareness of blood sugar at any given time is invaluable for preventing severe high or low blood sugar events.

The Evolution of AID Systems

The first AID system to market was the Medtronic 670G in 2017. In this system, the Medtronic Guardian 3 CGM sends interstitial glucose values every 5 minutes to the insulin pump. From there, the insulin pump works on a proprietary algorithm to constantly adjust the insulin to a target blood sugar of 120 mg/dL. This setting is called “auto mode.” Like other insulin pump systems, individuals still interact with the insulin pump to bolus for meals eaten.

The Medtronic system was an exciting milestone in the diabetes community, but as is the case with most new or first technology, it encountered red tape from the FDA, which had potential safety concerns around the system’s automatic mode. Before approval the FDA required that several safety features be put in place to trigger an exit from auto mode back to “manual mode.” In manual mode, the insulin settings are placed by the prescribing health care provider and do not auto-adjust in response to information from the CGM.

The diabetes community has learned a great deal since 2017, with one of the major takeaways being that auto mode is extremely safe—even safer than manual mode, since a person’s insulin needs can vary on a day-to-day basis and the AID system is able to flex with these changes continuously.

In 2019, the diabetes device company Tandem came out with its AID technology, called Control IQ, in which the company’s t:slim X2 insulin pump was able to interact with the Dexcom G6 CGM in a control algorithm targeting a blood sugar range between 112.5 mg/dL and 160 mg/dL. Third to market and most recent is Insulet Corporation’s Omnipod 5 system, which pairs a tubeless insulin pump with the Dexcom G6 CGM.

What the Research Shows

Overall, the research studies investigating AID systems for people with type 1 diabetes (T1D) have shown some major advantages over multiple daily injections of insulin. One of the advantages of AID systems is that it improves the time spent in the person’s desired blood sugar range. Because the systems are constantly adapting to minor fluctuations in blood sugar levels, they are able to more closely mimic what a normal pancreas making insulin might do. The second major advantage is that they have been shown to decrease rates of low blood sugar, or hypoglycemia.

According to the American Diabetes Association (ADA) Standards of Medical Care 2022 guidelines, AID systems “should be offered to youth and adults with type 1 diabetes and other types of insulin-deficient diabetes who are capable of using the device safely”. The data on safety and efficacy speak volumes on how much these systems have improved the lives of many people with type 1 diabetes.

On the Horizon: Insulin and Glucagon

Next to market will likely be artificial pancreas systems that not only contain insulin but another hormone called glucagon. Insulin is the hormone that brings blood sugar down, and glucagon does the opposite and increases blood sugar. Elegant algorithms incorporating both hormones are under investigation.