I am new to pumps, recently starting on an Omnipod 5 with a Dexcom sensor. I thought I was doing okay, showing 6.7 GMI with 85% TIR, but my A1c just came back as 7.1. I am thinking the solution is a daily calibration to make sure the sensor is accurate.
Are there better solutions, and how do others keep their sensor accurate?
I don’t have an answer for you but have a similar problem. My A1c is usually 5.7-6.0 and my GMI is usually 6.7-6.8. it’s a different calculation altogether so I just try to keep my average BG down as much as I can and don’t worry too much about the longer-term stats.
Edit - I don’t think calibration is the answer if you are checking with a meter and the number matches with your CGM. Obviously if it doesn’t match, you should calibrate.
GMI is based upon sort of an average of blood glucose measured every 5 minutes. HbA1c is the percent of hemoglobin that has been glycosated becoming hemoglobin A1c. While GMI is an average of BG, HbA1c is not. Worse the GMI is an estimate of HbA1c.
It’s kind of apples and oranges. The 2 metrics do not measure the same thing. The spread between your GMI and HbA1c are not way out of bounds. For some people they will be the same or a point different, but not all people.
This image shows the possible variables of an HbA1c of 7.0% correlated to time in range. I am more concerned about being in range than HbA1c numbers.
(upload://7cT5AyKFMbJdZTxuOzrVL0mM93H.jpeg)
Here’s a screenshot of my last 14 days from Dexcom Clarity app.
The standard deviation is how much my blood glucose was above or below the average. BTW my last HbAic an month ago was 6.4% the same as this GMI.
I don’t think your issue is inaccurate sensors. A lower A1c comes from a lower average BG, especially in the few weeks before the A1c measurement. To get a lower average BG requires more insulin. More than the Omnipod 5 will give by itself, because the algorithm won’t risk driving the BG low, whereas we can take larger manual doses of insulin to curtail a BG rise that may result from an increase in insulin resistance or to compensate for impaired insulin absorption or leaking at the cannula. We can take a larger insulin dose because we can take fast carbs if/when it turns out that we took too much.
A way to lower A1c is to limit BG rises by more aggressive dosing, while being prepared to counteract the BG drop with fast carbs when too much insulin has been taken. Don’t worry about the difference between GMI and A1c, just work to reduce the magnitude of BG excursions and the BG average.
