Fort Berthold Diabetes Program

New Innovations: Freestyle Libre Continuous Glucose Monitoring 

Gwendolyn Davis, RN – Case Manager


Many people are beginning to inquire about the new glucose monitoring technology that has hit the market recently, known as the Libre Freestyle 14-day system.  This system allows the person with diabetes to apply a sensor to the back of the arm that adheres to the skin for up to 14 days.  During this 2 week timeframe, the sensor measures glucose levels through the interstitial fluid that comes from the body’s tissues.  This gives an opportunity for checking the glucose levels painlessly every minute, without the hassle of having to use a lancet to poke the finger. Please note, people who use the Libre system should continue to have their blood glucose meters readily available as a back-up to the Libre system.  Another great perk about the Libre system is that a cell phone app can be used in lieu of the reader to scan and record glucose readings.  How terrific it is to be able to carry around one less item for diabetes management!

At times, those who are physically active or who have physically demanding jobs may have trouble with the sensor adhering for the full 2 weeks.  A few suggestions for helping the sensor adhere for the 2 week timeframe include: 

  • Take a shower, exfoliate the skin on the back of the arm, let the area dry for 30 minutes, and cleanse the area with BOTH included alcohol swabs for at least 30 seconds per pad.  Do not get the sensor wet until the next day, to allow the adhesive to completely stick. 
  • Try an adhesive patch that can offer an extra layer of protection when wearing the sensor. An example would be SIMPATCH adhesive patches that can be purchased off for around $17 for 25 patches. These patches come in a variety of colors and are waterproof. 

Frequently asked questions:

Has the FreeStyle Libre 14 day system been tested in (a) water and (b) sea water? 

  • Yes. Sensors can be worn while bathing, showering or swimming. Don’t take sensors deeper than 3 feet or for longer than 30 minutes. b) No. The FreeStyle Libre 14 day system has not been tested in sea water.

What are FreeStyle Libre 14 day system’s contraindications? 

  • Remove the sensor prior to MRI, CT scan and direct exposure X-rays (see note below).  

 Note: The Abbott Diabetes Care engineering team has indicated that if the sensor is not ‘exposed’ directly to the X-ray, such as covering the sensor with a lead shield to avoid X-ray exposure, performance of the sensor should remain intact.  Since the sensor is not directly exposed to the X-ray during a mammogram, it does not need to be removed when patients undergo this diagnostic. The Diabetes Program recommends removing the sensors for these diagnostic procedures. 

What substances could interfere with the results generated by the FreeStyle Libre 14 day system? 

  • Doses of aspirin greater than 650 mg may negatively impact sensor glucose readings. 
  • Do not take high doses of vitamin C (more than 500 mg per day), as this may falsely raise your sensor readings.  If you take Emergen-C packets, those are 1,000 mg. 

What are the differences between interstitial fluid (ISF) and blood glucose (BG) readings? 

  • Interstitial fluid glucose measurements are taken from the fluid within tissue while blood glucose measurements are taken directly from the blood. Sensor glucose values, which are based on interstitial fluid glucose levels, can be different from blood glucose levels (finger sticks), particularly during times when your blood glucose is changing quickly. For example after eating, taking insulin, or exercising. When glucose levels are falling quickly, glucose readings from the Sensor may be higher than blood glucose levels. On the other hand, when glucose levels are rising quickly, glucose readings from the Sensor may be lower than blood glucose levels.

Interstitial fluid lags behind blood glucose by approximately 15 minutes. 

Readings will NEVER be exactly the same.

What happens to the sensor if it is worn outside of the recommended temperature range? 

  • If the sensor stops working due to extreme temperature the reader will display an error message. The sensor will resume recording glucose readings again once it is within the temperature range again. The Operating temperature is between 50 °F to 113 °F. 

What is the best positioning of the arm to apply the sensor? 

  • When self-applying the Libre sensor, it is best to put your arm in the flexed muscle position, while ensuring you are applying the sensor to the fatty underside of the arm, NOT the muscle as this can lead to possible bleeding and bruising.  

To make an appointment or for assistance with diabetes management/nutrition, please call the Diabetes Program at 701-627-7931. Visit for a Libre instructional video and the Libre Important Information sheet!