Continuous glucose monitors were built for one job: helping people with diabetes manage insulin dosing without finger sticks. That's still their best-supported use. But over the last few years, a second market has grown up around them — healthy adults wearing a CGM to "optimize" energy, sleep, or weight, with no diabetes diagnosis at all.
The appeal is obvious. A glucose curve is a number you can watch move in real time, and that feedback loop is satisfying in a way that annual bloodwork isn't. Whether it's clinically useful for someone with normal glucose regulation is a separate question.
What the data actually shows
Glucose variability in people without diabetes is wide and mostly unremarkable — spikes after refined carbs are normal physiology, not evidence of dysfunction. Most consumer CGM apps have no way to distinguish a meaningful pattern from ordinary variation, so they tend to flag both.
A device can be genuinely useful for one population and mostly noise for another. The hardware doesn't change — the interpretation does.
Where it's reasonable to consider one
For people with prediabetes, strong family history, or specific metabolic concerns their physician is already tracking, a short monitoring period can add real information a single fasting glucose test misses. Used that way — as a defined-duration diagnostic tool rather than a permanent accessory — a CGM earns its place.
The technology isn't the problem. Treating a continuous data stream as inherently more meaningful than a single good test, without asking what question it's actually answering, is.