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Sensor Glucose and Blood Glucose: What's the Difference?

By Karrie Hawbaker

Public Relations Manager

Posted:  5/27/2014 7:17 PM


Many of you have been wondering what the difference is between sensor glucose and blood glucose values. To help give you a better understanding, this video demonstrates and explains why the two values will rarely match and are expected to be different. Have questions after watching the video? Let us know in the comments below.


Rebecca Russo

Posted on Wed May 28 00:35:09 GMT 2014

Occasionally, my BG and SG will differ by 100 points, or more. I understand the roller coaster concept, however, it would be great to have something more dependable to rely on. I still test my blood glucose at least a dozen times a day and my HA1C is 5.4 so guess I'm doing OK.

Angela Hebbelman

Posted on Wed May 28 03:16:37 GMT 2014

This is good information. It makes understanding the values a bit better and why they differ.

Hal Maloy

Posted on Wed May 28 07:01:42 GMT 2014

Very nicely done and comprehensive. I can't wait to get mine! I am waiting to see if affordable care act will cover the new pump. Especially the sensors, which I was told cost like $300.00 + for one of them.....or was it 10 of them. Nevertheless, VERY expensive for an insurance to pay for.


Posted on Wed May 28 16:17:00 GMT 2014

Hi Rebecca, when glucose levels are rising or falling quickly, there may be a larger difference between your BG and SG meter values, such as after meals or taking a bolus of insulin. You may also find this information helpful: I will have someone from my team connect with you to try and help.

Angela, I’m glad this video was helpful for you!

Thanks for the feedback, Hal. We have a team of people here who would love to help you with submitting to your insurance. We also offer financial assistance for those who qualify. Let me know if you’d like to discuss your options, and I’d be happy to connect you with someone.


Posted on Wed May 28 17:21:02 GMT 2014

I get this part. What I can't get a clear answer on is why when my blood glucose is steady (over several hours) that the SG can remain 50-100 points different. I'm seeing this happening more and more often and the way I monitor, calibrate, etc. has not changed.


Posted on Wed May 28 17:58:33 GMT 2014

The roller coaster model makes sense most of the time. But I frequently find that my BG (tested every 2-3 hours) is steady, but the SG rises 50-80 points. I can't find anything to explain this.


Posted on Wed May 28 22:43:00 GMT 2014

Jeannine and Greg, I am sorry to hear you’ve been experiencing this, and understand your frustration. I will make sure to have someone from my team contact you shortly to help out. Please let me know if there’s anything else I can help you with.

Mary Elizabeth

Posted on Thu May 29 12:11:52 GMT 2014

That comparison made a lot of sense. It was very helpful.


Posted on Mon Jun 02 18:31:20 GMT 2014

Glad you found the SG and BG comparison video helpful, Mary! We are committed to delivering more of the content that our community wants to see, so keep checking back.


Posted on Thu Jun 05 16:17:39 GMT 2014

Like Rebecca I too experience differences of more than 100 points between SG & BG. When it happens my SG is the lower # and BG is the higher #. Today my 8 am BG was 224 and SG 124. The trend line overnight was fairly steady but in the 120 range on the graph. I did a calibration. At 11 am my BG was 282 and my SG was 120, again with the trend line fairly steady in the 120 range. I received NO alarms. My sensor is 3.5 days old. I contacted Medtronic to find out why I didn't get an error that the BG & SG were so different. After 45 minutes speaking with Christina, the only thing she could suggest was to change my sensor. When I asked her why I didn't get any alarms, she said the pump isn't setup to give those kind of alarms. Shouldn't I get a calibration error if the BG & SG are more than 100 points different for more than 3 hours? I am beginning to rely on that trend graph for knowing when my BG is going up or down. Am I going to have to go back to testing 6-8 times a day like Rebecca??? If so, then what's the advantage of the sensor?


Posted on Thu Jun 05 21:39:41 GMT 2014

Hi Debbie. I understand this can be frustrating. We do recommend calibrating 3 to 4 times a day for optimal sensor performance. You may find this information on why sensor readings are different from BG readings helpful: You may also find this article from one of our customer’s initial experience using the system helpful, too: I will have one of our advanced specialists connect with you to try and help. Please let me know if there’s anything else I can help you with.

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