Today marks day 168 of Project Food as Fuel. For the uninitiated, feel free to get caught up with this post. 

Imagine going to a busy freeway to report on traffic. You show up once per day and take one picture. You pick different times for each visit. After a month, you show the pictures to someone else. Will that person know what the traffic is like on that freeway? One picture each day will give you a general idea of what’s going on. A set of 30 pictures will give you a rough summary of what traffic is like on the road. But these are not enough data points for true trending. You will miss lots of accidents and potentially other trends due to time of day and other factors. 

I have been checking blood glucose and ketones once per day every day with the Precision Extra device. Anyone can buy one of these devices over the counter at a pharmacy. I log these values into an app and have a rough picture of my glucose control. But one data point each day for blood glucose is simply not sufficient to get a true measure of what’s going on.

I decided it’s time to gather more data with a device called a continuous glucose monitor (CGM). The CGM is a sensor that attaches to the body and monitors blood glucose by taking a reading every minute. From one data point in a day to 1440!

Purchasing a CGM is more complicated than purchasing an over-the-counter glucose monitor. For one, a CGM requires a prescription from a doctor. Thankfully, my doctor with Virta Health Clinic sees the value in the data collection and my willingness to use this tool to improve my health. He called in the prescription.

The second challenge is the price. I am not a Type 1 diabetic, and I am not taking insulin. These are generally the two scenarios in which medical insurance will deem medical necessity to cover a CGM. I already know my insurance will not cover the device, so I’m paying out of pocket. The doctor recommended the FreeStyle Libre 14 day system. 

I don’t exactly know how it works, but there is a website called GoodRX.com that offers coupons for prescription drugs and devices. Based on my research, it seems that Walmart offers the lowest price, so that’s where I had the doctor send the prescription. I printed the GoodRX coupon and headed to Walmart. It’s a good thing I used the free coupon. The cash price without a coupon is US $240 for the Libre with two sensors. I paid US $135. Where they get you is the sensors. Each sensor lasts 14 days. They can probably last longer but are electronically limited to 14 days. Two sensors cost $70, which will be the monthly cost of this experiment.

When I got home I read the instructions for applying the sensor. The sensor is a small disc that is applied with an applicator to the back of the arm. There are small metal wires that are inserted into my tissue.  I was able to apply it without an issue or pain. It takes an hour for the sensor to calibrate and then it’s off to the races. 

A CGM works by measuring glucose in the tissue of the body as opposed to direct sampling of the blood. As a result, the reading from a CGM at any given moment may not be as accurate as a finger prick. In addition, the FreeStyle Libre is not a real-time sensor like other models that alert you when your blood sugar is going high or low. In order to get a reading, I need to take the small reader device and hold it near the sensor. It also works with an app using NFC technology on iPhone/Android phones.

Neither of these limitations presents a challenge for me. I’m not dosing with insulin, and I am not worried about hypoglycemia or hyperglycemia. What I am interested in is the trend throughout the day and evening. I want to see how my glucose values change after meals, exercise, and even sleep. 

When I check numbers once a day, I can sometimes game the system for a favorable result. Maybe skip a meal or having something naughty after checking my numbers for the day knowing I can balance out by the next day. Now there is no place to hide with 24/7 monitoring. I did tell my health coach that I may end up eating some foods that I wouldn’t normally eat “in the name of science.” 

Let the experiment begin!