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A man wearing a continuous glucose monitor on his arm with a confused look on his face.

3 Tips for Those Who Self-Start a Continuous Glucose Monitor

A number of people with type 2 diabetes are now gaining access to flash or continuous glucose monitor systems (CGMs). Yet, as is typical for those living with type 2 diabetes, few people get support or training on these devices.

How does a continuous glucose monitor work?

To be fair, many of these systems are considered “self-starts”. That’s a fancy way of saying you’re given the information and tools you need by the company to get the equipment up and running on your own. What “self-starts” don’t do is help you understand and maximize your device, which is why I often observe gaps in people’s understanding of their CGMs. This can lead to frustration or burnout on a device that could be life-changing.

So, whether you’re considering a CGM or new to a CGM, here are three tips on understanding your device.

1. Don’t overreact

When you first wear a CGM, you’re going to see more than you did before. Try not to panic and try not to overreact. One of the best things you can do is maintain your usual habits and routines and just observe what your glucose levels do over the first 1-2 weeks. For example, you’re going to see your glucose levels go up after meals and come back down a few hours later. That’s natural. But it’s easy to feel overwhelmed or concerned if your levels are higher than you expected or stay elevated longer than you expected.

Too often I see people new to CGMs get caught up in taking extra medication to “fix” higher glucose levels and end up with lows. I also see people change too many things at once and get frustrated when their glucose levels are all over the place (it’s tough to figure out what’s working and what’s not when you’ve moved too many pieces of the puzzle at once!). So, take your time in learning your new device and your personal glucose patterns.

2. It’s normal if it doesn’t match up to your glucometer

Many people don’t realize that a CGM measures the glucose level in your interstitial fluid. Interstitial fluid is fluid that sits between the cells of your body. This is different than a glucometer, which measures the glucose level in your blood. So, it’s natural that the readings on your CGM do not exactly match up with your blood sugar checks, because you’re measuring the glucose levels in two different areas of your body.

If your glucose levels are very stable (indicated by a horizontal arrow on your CGM), then you may see your readings be similar. If your glucose levels are rising or falling rapidly, then you may see a bigger gap between your blood glucose levels and CGM levels. Glucose shifts from your blood, to your interstitial fluid, then eventually to the cells of your body. So, there’s a lag time of about 10-15 minutes between the glucose level you see on your glucometer to the glucose level you see on your CGM.

3. Don’t toss your glucometer yet

Even though the most popular CGMs don’t require you to check blood sugars with your glucometer, it’s always a good idea to check if something seems off. False glucose levels can happen. One reason? In order for the CGM to be able to sense your glucose levels, there has to be enough interstitial fluid to measure. Without enough fluid to measure, you can get a falsely low reading. Being dehydrated can cause this to happen.

Another cause is pressure on your CGM (for example, wearing a tight belt or clothing over the area, or sleeping on your CGM). This pushes interstitial fluid away from the CGM sensor, leaving little for it to measure. On the flip side, some CGM systems can be affected by acetaminophen (the main ingredient in Tylenol, but also found in many over-the-counter medications). If your CGM device is sensitive to this (read your user guide), it can cause falsely high readings. So when it doubt, check it out (with your glucometer, of course!).

CGMs are a great tool and fairly easy to use.  But, like any new device (diabetes-related or not) it takes time to learn the ins and outs. Don’t be afraid to call the company and ask for help with understanding your device. And, most insurances, if they cover the cost of a CGM, cover the expense of seeing a diabetes educator for support and training on your new device.

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