Continuous glucose monitors have transformed care for people who use insulin, but their value for the much larger group of adults with type 2 diabetes who do not use insulin has been an open question. A large clinical trial published in the New England Journal of Medicine now offers the clearest answer yet: in the study, adults using the wearable sensors spent roughly five more hours a day in their target blood sugar range than those relying on standard monitoring. For a condition managed in small daily decisions, five hours is a substantial difference.
What the Trial Found
The study, described as the largest clinical trial of its kind, followed adults with type 2 diabetes who were not on insulin — the population that makes up the majority of people living with the condition. Participants given continuous glucose monitors, which read glucose from a small sensor worn on the body and send readings to a phone or reader, kept their levels in range for significantly longer each day than the comparison group. Details reported by the University of Colorado Anschutz Medical Campus underline the scale of the trial and the consistency of the improvement.
Time in range has become a favoured measure in diabetes care because it captures the shape of a whole day, not just a single average. A person can have an acceptable average while still swinging between highs and lows; spending more hours steady, in the target zone, is associated with feeling better day to day and with lower risk of long-term complications affecting the eyes, kidneys, nerves and heart.
Why Feedback Changes Behaviour
The technology itself does not lower blood sugar. What it changes is information. A finger-prick test gives a single number at a single moment; a continuous monitor shows a line — rising after a meal, easing after a walk, dipping overnight. Seeing, in near real time, how a particular breakfast or an evening stroll affects that line turns abstract advice into personal evidence. Researchers believe this feedback loop is the main reason the devices help: people adjust portions, timing and activity because they can watch the effect of each choice within the hour.
That learning effect fits with what exercise research shows elsewhere. As our article on Zone 2 cardio and its benefits explains, gentle, regular activity has an outsized effect on metabolic health — and a glucose monitor makes that effect visible, which can be powerfully motivating. Likewise, readers building strength alongside can pair these insights with our guide to strength training after 40.
Who Stands to Benefit Most
Not every person with type 2 diabetes needs a sensor, and clinicians caution that the devices work best when someone is ready to act on the data. The strongest candidates are likely to be people whose control is drifting despite medication, those making lifestyle changes who want to see what is working, and patients at risk of low blood sugar from particular medicines. For others, periodic testing and regular reviews may remain entirely reasonable, especially where cost or coverage is a barrier.
Cost is the central policy question raised by the trial. Sensors are consumables, replaced every one to two weeks, and extending them to millions of people who do not use insulin would be a major commitment for insurers and health systems. Supporters argue that better daily control pays for itself by preventing expensive complications years later; sceptics want longer follow-up data before such a wide rollout. This study strengthens the supporters’ case, but the coverage debate is unlikely to end with one trial, however large.
Practical Questions Before You Try One
Anyone considering a monitor should start with a conversation with their diabetes care team: which device, which target range, and what to do with the alarms and trend arrows it provides. It is also worth setting expectations. Readings from tissue fluid lag a few minutes behind blood readings, sensors occasionally fail or read inaccurately when compressed during sleep, and a constant stream of numbers can cause anxiety in some people. A short trial period — a few weeks of wearing a sensor purely to learn — is an approach many clinics now use, and this study’s results suggest even that kind of short, information-rich experiment can teach lessons that stick.
The broader message of the research is encouraging. Type 2 diabetes management has long depended on infrequent tests and general advice. Continuous monitors offer something different: personal, immediate and surprisingly understandable data. For the millions of adults managing this condition without insulin, five extra hours a day in a healthy range is not a gadget story — it is a meaningful improvement in everyday health, and a sign that better feedback may matter as much as new medicines.