Frequently Asked Questions (FAQ) Glucose & Ketone Meter

Important points before you start

Meter settings

• Make sure you work with the correct measurement ( mmol/L or mg/dL, depending on the purchased meter).
• Ensure you are using the correct test strips for glucose or ketones.
• Insert the correct calibration chip the first time you open a new box of strips.

Test protocol

• Wash and dry your hands thoroughly before testing.
• Always wipe away the first drop of blood; use the second drop.
• Let the tip of the strip gently touch the blood droplet—it will be absorbed automatically.

Helpful resources

• Instructional video
• User manual (PDF)
• Quick start guide

1. E‑4 Notification – Used or incorrectly handled strip

What do you see?

The meter displays error code E‑4.

What does it mean?

The strip was used incorrectly or has already been used.

Possible causes

• Blood was applied to the strip before inserting it into the meter.
• The strip was inserted upside down or backwards.

How to avoid this

• Insert the strip into the meter first.
• Wait for the blinking blood drop icon to appear.
• Apply blood only to the tip of the strip.

2. E‑5 Notification – Not enough blood

This error code indicates that there’s too little blood on the test strip to perform the test.

How can this happen?

a.) If you put the blood on the flat part of the test strip instead of touching it with the end of the test strip.
b.) If you press the test strip against your finger, so that the opening gets “clogged”. When the small opening in the strip is blocked, it can’t absorb the blood.
c.) If the drop of blood on your finger is too small.

If you find it hard to get a drop of blood that’s large enough, try the following.

• Before pricking your finger, rub your hands together well to warm them and make a fist a few times. This will increase the blood flow to your fingertips.
• Adjust the lancet’s piercing depth on your lancing pen. Please refer to the lancing pen’s manual for the correct way to do this.
• Don’t wait after pricking your finger. Just wipe off the first drop of blood and use the second one immediately.

The correct way of measuring is: 

1. Take a new and unused test strip and place it correctly in the meter.
2. Check whether the code on the screen matches the number of the test strip.
3. Wait for the droplet icon to flash on the screen.
4. Prick your finger with the lancing pen.
5. Wipe off the first drop of blood. You need to use the second drop.
6. Hold the meter with the inserted strip in the other hand. Then gently touch the drop of blood with the end of the strip.
7. The blood is drawn into the strip. You will see the channel inside the strip filling up.
8. The meter counts down and displays the test result.

Using the test strip

Don’t put blood or control solution on the flat top of the test strip. When you have a little round drop of blood on your fingertip, you can gently touch it with the end of the strip. You only need a small drop. Each test strip has a built-in tube (capillary) with an opening at the end of the strip. If you touch the drop of blood with this tube, it will absorb the blood. The meter then counts down and show the test result.

3. Measuring Glucose and Ketones with One Finger Prick

Yes, the Go‑Keto meter allows you to measure both glucose and ketones with a single finger prick.

How it works

• Blue code chip: for ketone testing.
• White code chip: for glucose testing (insert the first time you use a new box of glucose strips).
• Once calibrated, you can leave the blue chip in the meter permanently.
• You only need to insert the glucose chip again when starting a new box of glucose strips.

4. Different Values – Understanding your results

It is normal to see differences between your self‑test results and those from a laboratory, or even between two self‑tests.

Why can results vary?

• Sample type: The meter uses capillary blood (fingerstick), while laboratories often test venous blood.
• Technology: The Go‑Keto meter uses electrochemical analysis, whereas labs may use different methods.
• Timing: Glucose and ketone levels change throughout the day and are strongly influenced by food, exercise, and fasting.

Important to know

• Glucose values may be higher or lower depending on the time since your last meal.
• Ketone levels typically rise during fasting, low‑carb eating, or after prolonged exercise.
• Always test under consistent conditions to best track your personal trends.

The Go‑Keto meter is designed for monitoring trends over time, not for exact one‑to‑one comparison with laboratory results.

5. Control Solution Test – Checking meter accuracy

The small bottle included in your starter kit is a control solution. Use it to check whether your meter and test strips are working correctly.

How to perform a control test

1. Shake the control solution bottle and place a drop on a clean surface (e.g., your fingertip or a piece of tissue).
2. Insert a test strip into the meter.
3. Touch the tip of the strip to the drop of solution.
4. Wait for the countdown (about 8 seconds).
5. Read the result displayed on the screen.

6. How to switch the Go-Keto/GK Dual meter between mmol/L and mg/L?

It is not possible to change this in the meter’s settings. When you purchase a Go-Keto meter or GK Dual meter, you choose either the mmol/L or the mg/L model.
Ketone values are measured in mmol/L by default. But this is different for the measuring of glucose values. The standard used depends on the country where you live.

Which meter should I choose?