If you have diabetes, you know individual blood glucose readings well. But a fingertip reading is only a snapshot. What happens between two measurements stays hidden: how much does your level rise after breakfast? How long does it take to come down again? And does your body react to pasta the same way as to bread? A glucose sensor like the FORA Connect 21 measures around the clock and makes this pattern visible. This guide explains how it works, what you can learn about your body and what to keep in mind. All information is based on the manufacturer's information and scientific studies. You will find the sources at the end of the article.
Who is the FORA Connect 21 for?
The FORA Connect 21 is a continuous glucose monitoring (CGM) system for people with type 1 and type 2 diabetes aged 4 and older. Children aged 4 to 12 use it only under the supervision of an adult [1].
How does the sensor work?
The sensor is applied only to the back of the upper arm and stays there for up to 21 days. It measures glucose in the interstitial fluid under the skin every 5 minutes and sends the values via Bluetooth to the app on your smartphone. After application it is ready to use in about 15 minutes. No routine finger pricking for calibration is needed during the wear period [1].
Instead of individual points, you get a continuous curve: day and night, at meals, during exercise and while you sleep.
What you can learn about your body
How your body reacts to food
After a meal, blood glucose rises and then falls again. With the sensor, you see exactly what this pattern looks like for you:
- how fast your level rises after eating,
- how high it goes,
- how long it takes to return to your starting level.
This helps you get to know your body better, because people react very differently. In a study of 800 people whose glucose was measured continuously for a week, participants reacted very differently to identical meals [2]. What barely causes a rise in one person can have a much bigger effect in another. General tables therefore say little about how your own body reacts. The sensor shows you.
How exercise affects it
Exercise also leaves its mark on the curve. A review of several studies showed that when long periods of sitting were broken up with short, light walks, blood glucose rose less after a meal than with uninterrupted sitting [5]. With the sensor, you can see for yourself what a walk after lunch does for you.
What happens day and night
Because the sensor also measures at night, you see your pattern over 24 hours, including times when you would never prick your finger. The app shows your values as a curve and summarises them in reports, for example as time in target range (Time in Range) or as a daily profile (AGP). You can set alerts for high and low values [1].
How do I interpret my values?
An international expert consensus recommends that most people with type 1 or type 2 diabetes spend more than 70 % of the time between 3.9 and 10.0 mmol/L [4]. The targets that apply to you personally should be agreed with your doctor.
For comparison: a study measured glucose patterns with a sensor in 153 people without diabetes (aged 7 to 80). Their average was 5.4 to 5.5 mmol/L, and about 96 % of the time their values were between 3.9 and 7.8 mmol/L. They were above 7.8 mmol/L for about 30 minutes a day on average [3]. Short rises after meals therefore happen in everyone. What matters is how high and how long.
Sensor versus finger prick: the difference
The sensor does not measure in the blood but in the interstitial fluid. Glucose reaches the tissue from the blood with a short delay: in healthy adults it is about 5 to 6 minutes [6]. When levels change quickly, for example right after a meal or during exercise, the sensor value may therefore differ slightly from a finger-prick value.
Also check with a blood glucose meter if a value does not match how you feel or if you are making important decisions, for example about insulin [1]. How to measure accurately is explained in our guide Measuring blood glucose correctly: 8 tips for accurate results.
Tips for meaningful insights
- Log meals, exercise and medication in the app. The app has an events feature for this [1]. This lets you match the curve precisely to what you did.
- Compare. Eat the same meal on two days, once with and once without a walk afterwards, and compare the curves.
- Look for patterns, not single peaks. Individual values fluctuate. What repeats over several days is what tells you something.
- Discuss your data. You can share your values with your doctor or family, or take them along as a report [1]. Do not change your treatment on your own.
When should you seek medical advice?
- If your values are often or for long periods outside your target range.
- If a value does not match how you feel.
- Before changing any medication because of a measured value.
The sensor does not replace medical care. It helps you understand your body better and discuss your values with professionals.
Frequently asked questions
Do I need to prick my finger with the sensor?
No routine finger pricking for calibration is needed. For a check, for example if a value does not match how you feel, a blood glucose meter is recommended [1].
Can I shower or swim with the sensor?
Yes. The sensor is protected against water (IP58). Showering, bathing and swimming are possible [1].
How long does a sensor last?
Up to 21 days. It is then replaced with a new one. The sensor and applicator are single-use items and must not be reused [1].
What should I keep in mind after applying it?
Keep the sensor dry and free of sweat for the first 24 hours. This helps it stick better and give a more stable signal. Some people are sensitive to adhesives, so do not choose exactly the same spot for your next sensor [1].
Does the app warn me about values that are too high or too low?
Yes. You can set your own thresholds for high and low alerts. There is also a predictive alert function [1].
What do I need?
A smartphone with Bluetooth (Android 9.1 or later, or iOS 15.6 or later) and the app, which you download via the QR code in the quick guide. The pack contains the sensor with applicator, adhesive patch, alcohol wipe and quick guide [1].
Can anything affect the measurement?
Taking ascorbic acid (vitamin C) can affect the readings. Before an MRI or CT scan, the system must be removed completely [1].
Learn more
- FORA Connect 21 glucose sensor: 21 days, no finger pricking, with app
- For finger-prick check measurements: Measure blood glucose
Free shipping from CHF 50 throughout Switzerland and to Liechtenstein.
Sources
[1] ForaCare / Smart OTC GmbH: FORA Connect 21, product brochure (2026) and quick user guide (version 2026.03), plus product information from the distribution partner. Information on intended use, wear time, measuring interval, warm-up time, calibration, water protection, app features, application and safety notes.
[2] Zeevi D, Korem T, Zmora N, et al. Personalized Nutrition by Prediction of Glycemic Responses. Cell. 2015;163(5):1079–1094. https://doi.org/10.1016/j.cell.2015.11.001
[3] Shah VN, DuBose SN, Li Z, et al. Continuous Glucose Monitoring Profiles in Healthy Nondiabetic Participants: A Multicenter Prospective Study. The Journal of Clinical Endocrinology & Metabolism. 2019;104(10):4356–4364. https://doi.org/10.1210/jc.2018-02763
[4] Battelino T, Danne T, Bergenstal RM, et al. Clinical Targets for Continuous Glucose Monitoring Data Interpretation: Recommendations From the International Consensus on Time in Range. Diabetes Care. 2019;42(8):1593–1603. https://doi.org/10.2337/dci19-0028
[5] Buffey AJ, Herring MP, Langley CK, Donnelly AE, Carson BP. The Acute Effects of Interrupting Prolonged Sitting Time in Adults with Standing and Light-Intensity Walking on Biomarkers of Cardiometabolic Health in Adults: A Systematic Review and Meta-analysis. Sports Medicine. 2022;52(8):1765–1787. https://doi.org/10.1007/s40279-022-01649-4
[6] Basu A, Dube S, Slama M, et al. Time Lag of Glucose From Intravascular to Interstitial Compartment in Humans. Diabetes. 2013;62(12):4083–4087. https://doi.org/10.2337/db13-1132
