Diabetes and prediabetes
Can a CGM help with type 2 diabetes if you are not on insulin?
It can, as a learning tool. A continuous glucose monitor shows how your own meals, walks, sleep and stress move your blood sugar through the day, which no general food list can. Over-the-counter monitors are now available for adults who do not use insulin, and a dietitian can help you turn the readings into changes.
Clinically reviewed by Dr. Ambily Kushal, RD, MS, PhD · Published · Last reviewed
What does a CGM do?
A small sensor worn on the arm or belly measures glucose every few minutes, day and night, and sends the readings to your phone or a reader.
Instead of one finger-stick number, you see the whole curve: how high blood sugar rises after a meal, how long it stays up, and what it does overnight. The sensor reads fluid under the skin, so it lags a finger-stick reading slightly.
Who can get one without insulin?
In 2024 the FDA cleared the first over-the-counter CGM for adults who do not use insulin, and prescription monitors are also available.
Whether a monitor is worth it, and for how long, is a good question for your doctor and dietitian. Many people learn most in the first few weeks, then use one again when something changes.
What can I learn from it?
Which of your own meals cause the biggest rises, how much a short walk after eating helps, and how late dinners or poor sleep show up the next morning.
- Compare two versions of the same meal, such as with and without a protein added.
- Try a 10 to 15 minute walk after a meal and compare the curve.
- Look at your fasting readings after early and late dinners.
- Notice the effect of stress, illness and poor sleep, not only food.
Should I adjust my diabetes medicine from CGM readings?
Don’t stop or change a prescribed medicine on your own. Any change to a medicine is a decision for the clinician who prescribed it.
Share your CGM reports with your doctor. They decide whether any medicine should change, and your dietitian helps you change the meals and routines behind the numbers.
What did this look like for one patient?
A vegetarian man on metformin, not insulin, used a CGM from his first nutrition visit and found that breakfast caused his largest rise of the day, while eggs alone barely moved it.
Combined with protein first, an earlier dinner, strength training and walks after meals, his A1c went from 7.9 to 5.9 over a year while his physician reduced his metformin. It is one person’s course, not a promise of results.
What patients say about this kind of care
Seeing your own glucose curve makes the link between a meal and a number concrete.
“She took time to break down the science of it all. I can now understand how one thing affects the other.”
Readings are only useful once they become a plan for what to eat next.
“She works with you to identify the root causes and then creates an action plan.”
Excerpts from patient reviews of Dr. Ambily Kushal, quoted word for word. Each describes one person’s care; individual experiences vary and are not a promise of results.
Frequently asked questions
Does a CGM replace an A1c test?
No. A1c shows your average over about three months and is how your doctor tracks diabetes. A CGM shows the daily detail behind that average.
What is a normal rise after a meal?
Targets differ by person and by medicine. Your doctor can tell you the ranges that apply to you, and your dietitian can help you work toward them.
Can a CGM help with prediabetes?
It can show how your meals affect you, but there is less evidence for monitors in prediabetes. Talk with your doctor about whether one is useful for you.
Do I need to wear one all the time?
Not usually without insulin. A few weeks at a time, with a clear question to answer, is often enough to learn from.
Sources
- Continuous Glucose Monitoring (National Institute of Diabetes and Digestive and Kidney Diseases)
- FDA Clears First Over-the-Counter Continuous Glucose Monitor (U.S. Food and Drug Administration)
- The A1C Test & Diabetes (NIDDK, National Institutes of Health)
- Advice to walk after meals is more effective for lowering postprandial glycaemia in type 2 diabetes (Reynolds et al., 2016) (Diabetologia)
Related reading
Our condition guides are general education, not medical advice. Talk with your doctor about your own diagnosis, tests and medicines.