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CGM; the real MVP

Updated: Mar 18, 2020

See below for the most PERFECT example of why CGM’s are a necessary part of DM control.

This patient has type 2 diabetes and is on multiple oral medications and basal insulin. Though he was instructed to test a minimum of 4x/day, life got in his way and he was, instead, testing his fasting blood glucose levels only. Unfortunately, I see this quite often. Life gets busy, and diabetes takes a back seat.

His self-monitoring blood glucose (SMBG) report showed his fasting control to be fair, however his most recent HbA1c was double digits. I knew something was off and decided to do a professional CGM on him (blinded 2-week CGM). The results of this Libre pro are on the final picture. Though his fasting readings (circled) were mostly <180mg/dl, he was suffering from extreme hyperglycemia the rest of the day. He had no idea!

The importance of blood sugar control in a PWD is critical for success in diabetes care and knowing the BG value is the first step in this.

Even if a PWD tests their BGs 4x/day with SMBG, that means that each of these readings is being used to manage ~6hrs worth of BGs and treatment. The above example shows how many BG variations can happen in that time.

Studies have shown that frequency of SMBG is directly related to control (the more SMBGs in a day, the better the persons glucose control). However, even with more frequent testing it is impossible to consistently predict how diet, illness, exercise, and stress will affect blood glucose levels, and though frequent SMBGs can allow us to diagnose and treat hypo and hyperglycemia, it does not prevent it from happening.

CGM therapy allows for critical treatment adjustments to be made based on directional data (trend arrows) and glucose readings provided every 1-5 minutes. Additionally, the CGM provides a trendline with values from the previous days and weeks. Alerts are available to inform the user if a glucose level is above or below a previously set threshold (threshold alerts), approaching those thresholds (predictive alerts), or rising or falling at a rapid rate of change (rate of change alerts). These settings can all be individualized by the user and clinician and allow the user to be proactive regarding their blood glucose instead of reacting to bad blood sugars after they happen.

A CGM consists of 3 parts; A sensor, a transmitter, and a receiver. The sensor is placed by the user with an inserter and sits just under the skin (like an infusion set for a pump user). It is changed every 3-7 days depending on the type of CGM. Most transmitters are reusable and sit above the skin as an extension of the sensor. The sensor uses oxidative enzymes to read interstitial glucose levels which are converted to blood glucose levels. The information is then transferred to a receiver device, cell phone, or insulin pump to be viewed by the user.

Real-time CGM data can be shared with loved ones alerting them to hypo or hyperglycemia of the user. A nervous parent, for instance, can be alerted when their child’s glucose drops below 80mg/dl in the middle of the night giving them the ability to sleep without fear that their child is experiencing a hypo episode in the next room (I don’t think my mom slept through the night until I left the house).

Additionally, the downloadable data provides crucial information to clinicians allowing for more knowledgeable treatment changes.

Overall, in addition to providing increased glucose control, CGM therapy provides increased knowledge, peace of mind, and in this case, it may have saved this patient from future complications! I’m curious, what has CGM done for you?

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