Diabetes Technology

Diabetes Technology: CGM, insulin pumps and hybrid closed-loop systems explained

Clinical review: September 2026

A glucose graph can feel like a weather forecast with rather too many thunderstorms. Diabetes technology cannot make diabetes disappear, but it can turn scattered readings into a clearer story and, for some people, reduce the number of decisions that have to be made every day.

Three tools with different jobs

Continuous glucose monitoring, or CGM, measures glucose in fluid beneath the skin every few minutes and shows direction as well as a number. It helps reveal overnight patterns, delayed meal effects and hypos that may otherwise be missed. A sensor is a guide, not an oracle: confirm with a finger-prick test when symptoms and the reading do not match or the device asks you to.

An insulin pump delivers rapid-acting insulin through a small cannula. It replaces long-acting insulin with a programmed background delivery and provides meal and correction doses. This can offer flexibility, but it also means that interruption of insulin delivery can lead to ketones and diabetic ketoacidosis more quickly than on injection therapy.

Hybrid closed-loop systems bring a sensor, pump and algorithm together. The algorithm adjusts background insulin in response to sensor glucose and predicted direction. The word hybrid matters: meals still need announcing, settings still need reviewing, and illness, exercise, alarms and site failures still need human attention. It is an excellent co-pilot, not an autopilot.

What the evidence shows and what it cannot promise

Trials and real-world studies in type 1 diabetes consistently show that automated insulin delivery can increase time in range, especially overnight, and reduce time spent low. The best results are usually seen when training, reliable sensor use and individualised settings travel alongside the device. It cannot guarantee perfect glucose or prevent every hypo, and the right system depends on lifestyle, dexterity, alerts, phone compatibility, skin tolerance, cost and access to support.

Safety is part of the technology

Anyone using a pump needs a written backup plan, rapid-acting insulin pens or syringes, access to ketone testing and clear sick-day guidance. Repeated unexplained high glucose, vomiting, abdominal pain, rapid breathing, drowsiness or significant ketones needs urgent action according to the agreed plan. A sensor may make patterns easier to see; it does not make ketone safety optional.

A useful technology review

A review should look beyond the average: time in range, time low, overnight patterns, meals, exercise, alarm burden and whether the device is helping the person live more freely. The best device is not necessarily the newest; it is the one that fits the person and has a credible plan for training, supplies and troubleshooting.

Important safety note

Seek urgent assessment for vomiting, abdominal pain, deep or rapid breathing, marked drowsiness or high ketones, particularly if a pump may have stopped delivering insulin. Do not switch insulin settings or stop insulin without an agreed plan. This page is educational and not a substitute for individual device training.