CGM Accuracy Matters

Your Guide to Choosing a Reliable Continuous Glucose Monitor (CGM)

Why does CGM accuracy matter?

CGM accuracy is really important because the numbers you see from your CGM guide your daily diabetes decisions. It's important to know:

  1. Not all CGMs are created equally: Some are more accurate than others. A good CGM gives glucose readings that are very close to your actual blood sugar levels.

  2. The impact now: If your CGM readings are not accurate, you could miss or wrongly treat dangerous glucose events, like very high or very low glucose levels. This can lead to diabetic ketoacidosis (DKA) or severe hypoglycaemia, both serious and potentially life-threatening if not managed in time.

  3. The impact later: Over time, inaccurate readings can lead to glucose levels being out of the recommended range (between 3.9-10.0 mmol/l) too often, which increases the risk of long-term complications like eye, kidney, or nerve problems.

Thabo’s study: compared to fingerstick blood (capillary):

  • Thabo wears a new CGM on his arm for several days. Throughout the day, he does lots of fingerstick tests, sometimes every 15 to 30 minutes! Each time, he notes the reading from his fingerstick test and the number showing on his CGM at that exact moment. 

  • Researchers then compare these two readings to see how close the CGM is to real fingerstick blood sugar levels.

  • This type of study gives a good picture of how the CGM performs in everyday life, since it matches what people actually do at home.

Aisha’s study: compared to lab blood (venous):

  • Aisha’s study takes place in a hospital or research clinic. She’s also wearing a CGM, but instead of doing fingerstick tests, nurses draw blood from her arm (venous blood) at regular times, maybe every 15 to 30 minutes for several hours.

  • That blood is sent to a laboratory, where scientists measure glucose using very accurate equipment. These lab results are then compared to the CGM readings taken at the same time.

  • This gives researchers a sense of how the CGM performs against precise lab measurements, but it’s less like real life and sometimes lab blood shows lower glucose levels than fingerstick blood.