What is a hybrid closed loop insulin pump?

Hybrid Closed Loop (HCL) systems, also known as Automated Insulin Delivery (AID) systems, are a type of diabetes technology that help manage blood glucose by combining a continuous glucose monitor (CGM), a wearable insulin pump, and smart software that automatically adjusts insulin delivery. 

By using real-time glucose data to adapt insulin dosing, HCL systems can help reduce highs and lows, improve time in range, and ease some of the daily burden of managing type 1 diabetes.¹

How does a hybrid closed loop system work?

HCL systems are made up of three core components that work together in a continuous feedback loop.

Continuous glucose monitor (or sensor)

A continuous glucose monitor (CGM), also sometimes called a sensor or glucose sensor, is a small device worn on the skin, with a tiny thread-like filament being inserted into the skin upon application. The CGM (or sensor) then measures glucose levels in the interstitial fluid and sends the glucose value to the receiving device connected to your sensor.

Insulin pump

An insulin pump is a small, wearable device that delivers insulin throughout the day.

All insulin pumps deliver:

• Basal insulin (replacing your ‘background insulin’, by delivering small amounts of insulin continuously)
• Bolus insulin, or doses for things like meals or corrections

Pumps can be tubed or tubeless, and in an HCL system they receive instructions from the algorithm to automatically adjust insulin delivery.

Smart software (algorithm)

The algorithm is the ‘brain’ of the HCL system. It analyses glucose data from the CGM and determines whether insulin delivery should be increased, reduced, or paused.

Rather than relying on fixed insulin rates alone, the algorithm makes frequent, small                                         adjustments based on:

• Current glucose level
• Direction and speed of glucose change
• Individual insulin settings

Hybrid closed loop in practice

HCL systems work continuously in the background to respond to changing glucose needs.

Every 5 minutes, typically:

1. The CGM sends a new glucose reading.
2. The algorithm evaluates whether insulin delivery needs to change.
3. The pump adjusts insulin delivery.
4. The CGM then detects how glucose responds, and the loop continues.
    

Everyday scenarios

• Overnight: HCL systems can help reduce nocturnal hypoglycaemia by automatically lowering insulin when glucose drops.
• Exercise: Many systems allow temporary settings or activity features that adjust insulin delivery when glucose tends to fall.
• Travel or illness: The system continues adapting insulin delivery as routine, activity, or stress levels change.

How the Hybrid Closed Loop algorithm works

The algorithm is often the least understood part of an HCL system. In simple terms, it acts like an experienced assistant checking glucose trends and making cautious adjustments.

Instead of making large insulin changes, the algorithm:

• Looks at patterns over time
• Predicts where glucose levels are heading
• Adjusts basal insulin in small, frequent steps

Hybrid closed loop systems are not fully automatic. Users must still count carbohydrates and send a bolus dose via the system for meals and snacks.

Benefits of hybrid closed loop systems

Hybrid closed loop systems are designed to support people living with diabetes by automating many of the insulin adjustments that would otherwise require constant attention. By responding to real‑time glucose data and adapting insulin delivery throughout the day and night, these systems can help improve glucose outcomes while reducing the mental and physical demands of daily diabetes management.¹

Some of the key benefits include:
 

Lifestyle benefits

• Fewer manual insulin adjustments throughout the day
• Less decision fatigue and cognitive burden related to diabetes care
• Reduced worry about overnight glucose levels
• Support during routine changes, such as exercise or busy days
   

Clinical benefits²

• Increased time spent in target glucose range
• Fewer episodes of low blood glucose (hypoglycaemia)
• Improved HbA1c for many users
• More stable glucose levels with fewer highs and lows over 24 hours

Hybrid closed loop vs. multiple daily injections (MDI)

Both automated insulin delivery and multiple daily injections are established ways to manage diabetes, but they differ in how insulin is delivered and adjusted.

With multiple daily injections, insulin is manually delivered using pens or syringes, with fixed basal doses and adjustments based on glucose readings.

With hybrid closed loop systems, a pump works with a continuous glucose monitor to adjust basal insulin automatically in response to real‑time glucose levels.

HCL systems can help reduce highs and lows by making automatic, frequent insulin adjustments; in contrast, MDI relies entirely on manual decision-making.

Overnight, HCL systems can adjust dynamically to changing glucose levels, while MDI requires people to plan and dose ahead of time.

MDI does not involve wearing devices, which some people prefer, while HCL systems require both a pump and a glucose sensor to be worn.

The right option depends on individual needs, lifestyle, comfort with technology, and guidance from a healthcare professional.

Is a hybrid closed loop system right for me?

Automated insulin delivery systems can be a helpful option for many people managing diabetes, but they may not be right for everyone. Understanding who HCL systems are designed for, and what using one involves, can help you decide whether it’s worth discussing with your healthcare team.

HCL systems may be suitable for:

• Adults living with type 1 diabetes
• Children and young people under 18 years old living with type 1 diabetes
• People with type 1 diabetes who are pregnant or planning to become pregnant³

A healthcare professional should be consulted to determine whether an HCL system is appropriate.
 

Things to consider before getting started

While HCL systems offer a high level of automation, they still require active participation and comfort with diabetes technology. Important considerations include:

• Wearing two devices: an insulin pump and a compatible glucose sensor
• Responding to alerts and alarms
• Continuing to count carbohydrates and bolus for meals
• Spending time learning how the system works and how to troubleshoot
• Access to devices and prescriptions through the NHS, which may vary by region

Weighing both the potential benefits and the practical realities can help set realistic expectations and support long‑term success with an automated insulin delivery system. A diabetes healthcare professional can help assess whether HCL aligns with your treatment goals and lifestyle.

Omnipod® 5 Automated Insulin Delivery System

The Omnipod 5 Automated Insulin Delivery System is one example of a HCL system available in the U.K.

Omnipod 5 combines:

• A tubeless, wearable Pod, powered by the Omnipod® 5 Algorithm 
• A compatible CGM/sensor  
• A Controller 

These 3 pieces work together to create the Omnipod 5 Automated Insulin Delivery System, automatically adjusting insulin discreetly, day and night.

The system is designed to simplify insulin delivery without external tubing. 

Learn more about Omnipod 5 here.