Your first CGM sensor - from decision to first measurement
If you've reached this article, it means you've already made the decision to try a continuous glucose monitoring sensor. Congratulations - it's one of the best decisions you can make for managing your diabetes. I've seen hundreds of patients whose CGM monitoring has completely transformed their understanding of their own blood glucose.
But I know that the first purchase can be intimidating. There are multiple models on the market, unfamiliar technical terms, and practical uncertainties: Will it hurt? How do I apply it? What do I do if something goes wrong?
In this guide I'll walk you step by step through the entire process - from choosing the model to the first days of use. The difference from our general guide about CGM sensors is that here I focus exclusively on the first purchase experience: common mistakes, realistic expectations, and practical tips I give my patients before their first CGM experience.
Step 1 - Check if CGM is right for you
Before buying, talk to your diabetes doctor. A CGM sensor is recommended in most cases of diabetes, but there are situations where your doctor may suggest a different approach. In general, CGM is ideal if:
You have type 1 diabetes (CGM monitoring is recommended by all international guidelines)
You have type 2 diabetes with insulin therapy and want better control
You experience large blood glucose fluctuations that your glucometer doesn't capture
You have nocturnal or unrecognized hypoglycemia
You want to understand how food and exercise affect your blood glucose
If you're unsure, read Glucometer vs CGM Sensor - Which is better? for a detailed comparison. Or consult CGM for type 2 diabetes: Is it worth the investment?
Step 2 - Choose the right model for YOUR FIRST experience
For your first purchase, I recommend prioritizing: affordable price (test the concept before investing heavily), ease of use, and simple application. You'll have time to try more advanced models after you get familiar with CGM.
My recommendations for your first CGM sensor
Choice #1 for beginners: LinX CGM
Most affordable price - ideal for testing the CGM concept
Smallest sensor (22 mm) - less intimidating on first application
IP68 - no need to worry about showering (a common concern for beginners)
Simple application with included applicator
Choice #2: Sinocare iCan i3
Competitive price, at the same level as LinX CGM
Intuitive app, ideal for less technical users
Manufacturer with experience in glucose monitoring
If accuracy is a priority: Sibionics GS1
Excellent accuracy (MARD 8.83%), EU MDR CE certification
Large user community - many tutorials and tips online
Slightly higher price but justified by excellent accuracy
For a complete comparison between all models, see Top 5 CGM sensors Romania 2026.
Step 3 - Check compatibility with your phone
This is a step many people skip and then have unpleasant surprises. Before ordering, check on the product page that the sensor app is compatible with your phone.
General minimum requirements:
iPhone: iOS 14 or newer (iPhone 6s and later models)
Android: version 8.0 or newer
Bluetooth: 4.0 or newer (available on any phone from the last 8 years)
Important tip: Install the app before you receive the sensor. Create your account, get familiar with the interface, and read the help section. That way, when you receive the sensor, you'll be ready to activate it without hesitation.
Step 4 - Order a single sensor to start
The mistake I see frequently: patients order a large package of sensors (3-6 units) from the start to save money. I don't recommend this approach for your first purchase.
Order a single sensor (14 days). After this first experience, you'll know:
Whether the chosen model fits you in terms of size and comfort
Whether the app will suit you in terms of interface and functionality
Whether you're ready to continue with CGM monitoring long-term
Only after the first 15 days, move to a subscription or package for long-term savings.
Step 5 - Preparing for your first application
When you receive the sensor, don't apply it immediately. Allow 15 minutes for preparation:
What you'll find in the box
The sensor - packaged sterile, ready for application
The applicator - the device that inserts the sensor under the skin (single use)
Instructions - read them completely, even if they seem simple
Skin preparation
Choose the back of your arm (triceps area) - this is the location recommended by all brands
Clean the area with an alcohol wipe and let it dry completely (30-60 seconds) - this is critical for adhesion
Avoid areas with: excessive hair, scars, birthmarks, moles, recent tattoos
Avoid areas of intense friction: waistband, backpack straps, watch band on the same arm
The actual application
Application takes less than 5 seconds and is practically painless. The applicator inserts a very fine needle under the skin, which then retracts automatically. What remains is only a flexible filament (thinner than a hair) that measures glucose in interstitial fluid. After application, you feel absolutely nothing.
My tip #1 for beginners: Don't hesitate. Press firmly on the applicator. Most patients tell me after the first application: "That's it? I expected it to be much worse."
Step 6 - First hours and first day - what to expect
Here's what you need to know about the first hours with your CGM sensor:
«Warm-up» period - after application, the sensor needs 60-120 minutes to stabilize. During this period you won't receive measurements (or they'll be inaccurate). This is completely normal.
First 24 hours - accuracy improves progressively. Don't worry if values differ slightly from your glucometer on the first day. The sensor will become more accurate after stabilization.
Initial alerts - if you haven't configured alert thresholds, you might receive frequent notifications. Adjust the thresholds in the app to the values recommended by your doctor.
Physical sensation - you won't feel the sensor on your skin after application. If you feel persistent discomfort, contact support.
Step 7 - Interpreting data in the first week
This is the part where CGM will surprise you. You'll see:
Postprandial peak - how much your blood glucose rises after a meal (many patients are surprised)
Dawn phenomenon - the natural rise in blood glucose early in the morning, before waking up
Impact of exercise - how physical activity lowers your blood glucose (sometimes dramatically)
Nocturnal fluctuations - what happens to your blood glucose while you sleep
Important tip: In the first week, don't make major changes to your treatment or diet. Just observe and learn. Show the data to your doctor at your next appointment - it will be invaluable for adjusting your treatment.
Common beginner mistakes - and how to avoid them
Applying on wet skin - the sensor will come off prematurely. Wait until skin is completely dry after disinfection.
Obsessive glucose checking - resist the temptation to check your phone every 5 minutes. Set alerts and let the sensor do its work.
Panic at the first unexpected value - a single reading is not cause for alarm. Watch the trend (directional arrows), not the instant number.
Not adjusting alerts - default alerts can be too sensitive. Calibrate them to the thresholds recommended by your doctor.
Changing treatment without your doctor - don't adjust insulin doses based on CGM data without consulting your doctor.
Final tips
Your first CGM sensor is an experience that will change your perspective on your diabetes. The continuous information you receive is incomparably more valuable than the point measurements of a glucometer. My recommendation: start with a single affordable sensor (LinX CGM or Sinocare iCan i3), follow the steps in this guide, and after the first 14 days you'll know exactly whether and how you want to continue.
All CGM sensors on PrimeMedical.ro are delivered quickly throughout Romania, with card payment, transfer, or cash on delivery. If you have questions, our support team is available on the contact page.
Also read: Top 5 CGM sensors Romania 2026 | LinX CGM vs Sibionics GS1 | How much does a CGM sensor cost in Romania
