Blood Glucose Test: Too Little Blood



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I have to do daily fingerstick blood glucose tests because my insulin pump requires it for calibration. Fingerprick tests are perhaps one of the most common aspects of managing Type 1 Diabetes and also other types of Diabetes like LADA. Even if you don’t use insulin to treat your diabetes, you may do a morning blood glucose test as a way to monitor your fasting blood glucose (FBG). Often doctors recommend checking in the morning and then also 2 hours after meals, to see how your blood glucose is doing post mealtime as well. It can help to give feedback on how food, exercise, and medication alter glucose levels.

Now that there are CGMs like the Freestyle Libre (see my blog post about the Freestyle Libre) and Dexcom, some people are able to rely on those instead of having to do so much finger testing, but for my Medtronic Guardian 3 CGM, it requires calibrations every 12 hours typically. Maybe the next model won’t have such a frequent requirement for blood glucose tests. Typically, Medtronic Guardian 3 CGM tracks very close to my actual blood glucose levels and it does seem like I calibrate more than necessary. Calibration is all about aligning something to the actual value, but if it’s already reading really accurately, then why do I have to do it so frequently? I know that medical devices like insulin pumps are required to meet a lot of regulations (from the FDA, for example). I am glad that they are safe, even if it seems I have to calibrate more frequently than necessary.

The Right Size Blood Drop for Glucose Test

As you can see in the above photo, my glucose meter will display a message if the blood drop isn’t big enough. The test requires a small amount of blood, and after a lot of testing, I have a pretty good awareness of whether it looks like I have a big enough blood drop…. However, occasionally, I do get this error code. This meter (I’m using the Contour Next One glucose meter) is actually better than most because it does allow you to add more blood. However, it only waits a short amount of time for that. So if you don’t add more blood right away, you get this message.

Sometimes I have to use the lancet to prick a second hole in my hand (usually, I try a different finger), because the blood just isn’t coming out. Squeezing is not a good idea because it will leave a bruise. Pressing lightly nearby is usually how I get more blood to come out. But, sometimes I have to repeat the finger prick somewhere else.

The tips I’ve heard to avoid this issue are:

  1. Wash hands with warm water before hand.
  2. Adjust the setting on your lancing device to the “bigger drop” setting. The lancet will go into your skin a bit deeper. Most lancing devices are adjustable.

If you aren’t happy with your lancing device, try buying a different lancing device. There’s a lot of options. You don’t need to keep using the one that came with your meter.


If you smoke, you may find that it’s easier to test your blood sugar before smoking. Nicotine constricts the capillaries. I find that smoking or vaping marijuana (cannabis) has a similar effect as well. It’s always easier to get the right size blood drop for the test before hand. (I was looking for some scientific studies to reference here, but I did not find them, so this is just from personal experience.)

What’s your experience here?

Do you have trouble getting enough blood for the glucose test? Any tips that help with this issue?


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