Medtronic Australasia Pty Ltd.
97 Waterloo Road North Ryde, NSW 2113
Phone: 1800 777 808

CGM and Sensors

Continuous Glucose Monitoring and Sensors

What is a glucose sensor?

A glucose sensor is a tiny electrode that measures your glucose levels. It sits under the skin in your interstitial fluid, where cells get oxygen and nutrients, including glucose. Glucose sensors are easily inserted using an automatic insertion device: like many types of infusion sets, a needle is used to insert the glucose sensor. The needle is then removed leaving just the tiny flexible electrode under the skin. The glucose sensor is then connected either to a transmitter so that readings can be transmitted to your insulin pump or monitor, or a recorder for downloading to software once removed.

Do I still need to do fingerstick readings if I use glucose sensors?

Using glucose sensors does not replace the need for fingerstick measurements. You still need to use your blood glucose meter to confirm a Continuous Glucose Monitoring (CGM) reading before treating or to calibrate the CGM system.

What are the highest and lowest glucose alarm thresholds that I can set?

High alarm thresholds can be set as high as 22.2 mmol/L and the minimum low alarm threshold can be set as low as 2.2 mmol/L. High and low threshold ranges can be customised and you should discuss your personal threshold levels and alert settings with your healthcare provider. The high and low glucose alarms have to be at least .6 mmol/L apart. Remember, if you set your high glucose limit at 10 mmol/L, then you cannot set your low glucose limit greater than 9.4 mmol/L (170 mg/dL). Conversely, if you set your low glucose limit at 2.8 mmol/L) then you cannot set your high limit lower than 3.4 mmol/L

How long do glucose sensors last? Do they expire?

Each glucose sensor can be worn for up to 6 days at a time. Glucose sensors have a 6-month expiration date from the time they are manufactured. The expiration date is on the outside of the glucose sensor box and on each individual glucose sensor package.

What type of batteries does the transmitter use?

The transmitter has a self-contained battery, which can be recharged using the charger supplied, but cannot be changed. As it has a self-contained battery, the transmitter should be disposed of, or recycled, in accordance with local governing ordinances and recycling guidelines.

What is the lifespan of the transmitter?

If used continuously, the transmitter has a life of approximately 12 months.

Do I need to refrigerate my glucose sensors?

The Enlite™ glucose sensor can be stored at temperatures ranging between 2˚ and 30˚Celsius without the need for cooling. Our glucose sensors have been comprehensively tested to withstand extreme hot and cold weather shipping conditions in the “non-refrigerated” shipping boxes.” If you choose to keep your sensors in the refrigerator anyway, allow approximately 15 minutes for the sensor to warm up to room temperature before you use it. Glucose sensors must not be frozen.

Where should I wear a glucose sensor?

This can depend on what you’re wearing, your desired comfort level, individual preference or experience. You may want to avoid recent infusion sites. While many people choose the abdominal area, some people prefer the upper buttocks, as this location is less likely to be bumped or affected by clothing at the waistline. See the Enlite User guide for recommended locations of insertion for most reliable accuracy.

How will I know when the transmitter battery in my MiniMed® Veo™ is getting low?

When the transmitter reaches a low battery condition, it will notify the insulin pump or monitor. It displays a "LOW TRANSMTR" notification. From the first "LOW TRANSMTR" notification of a low battery, you have about 5 days of continuous use before the battery is completely depleted. You will then receive a "BAD TRANSMTR" notice, which means the transmitter battery has been depleted. See the Alerts & Alarms section for more information.

What is the operating range between the transmitter and the insulin pump?

The transmitter and insulin pump must be within approximately 2 metres (6 feet) of each other for wireless transmission to occur.

What happens when the MiniMed® Veo™ transmitter and insulin pump move out of range?

If the transmitter and insulin pump are too far apart (more than 2 metres or 6 feet), an alert will sound and either a "WEAK SIGNAL" or "LOST SENSOR" message will appear on the screen. The MiniMed® REAL-Time insulin pump and Continuous Glucose Monitoring (CGM) system allows you to set the period of time the insulin pump will wait before alerting you of a failed reception of CGM data from the transmitter to the insulin pump. The delay can be set between 5 and 40 minutes. The default setting is 30 minutes.

The transmitter holds 40 minutes’ worth of memory and if the transmitter and insulin pump are too far apart for longer than 40 minutes, reports will have a "data gap" where information is missing during this time period.

What happens when the MiniMed® 640G transmitter and insulin pump move out of range?

If the transmitter and insulin pump are too far apart (about 2 metres or 6 feet), an alert will sound and either a "LOST SENSOR SIGNAL” or “SENSOR SIGNAL NOT FOUND" message will appear on the screen. The transmitter holds 10 hours’ worth of memory and if the transmitter and insulin pump are too far apart for longer than 10 hours, reports may have a "data gap" where information is missing during this time period.

Is the radio frequency from my MiniLink™ transmitter harmful to me in any way?

The MiniLink™ transmitter uses about 1,000 times less radio frequency (RF) power than a mobile phone. When talking on a mobile phone, you are receiving a constant stream of RF transmission. In contrast, our transmitter sends very small transmission “bursts” which are not harmful.

Is the radio frequency from my GuardianLink® harmful to me in any way?

The GuardianLink® transmitter uses about 1,000 times less radio frequency (RF) power than a mobile phone. When talking on a mobile phone, you are receiving a constant stream of RF transmission. In contrast, our transmitter sends very small transmission “bursts” which are not harmful.

How do you turn off transmission from the MiniLink™ transmitter to the insulin pump?

The transmitter begins transmitting data as soon as it is connected with the glucose sensor. It also transmits data when the CGM on the insulin pump is off. Therefore, you should disconnect the glucose sensor from the transmitter. The glucose sensor can remain inserted.

How do you turn off the transmission from the GuardianLink® to the insulin pump?

The GuardianLink® begins transmitting data as soon as it is connected with the glucose sensor. The transmitter also transmits data when the CGM on the insulin pump is off. Therefore, you should disconnect the glucose sensor from the transmitter. The glucose sensor can remain inserted.

Transmitters and water

Is my GuardianLink transmitter waterproof?

When you’re wearing the GuardianLink® and it’s connected to the sensor, the transmitter is waterproof and fully immersible. However we do not recommend immersing it in very hot water e.g. hot tub. You can wear the transmitter to a depth of 8 feet or 2.4 metres for up to 30 minutes.

Can I immerse the MiniLink™ transmitter?

When connected to the sensor and worn, the MiniLink™ is waterproof and fully immersible. However, we do not recommend immersing your MiniLink transmitter in very hot water, e.g. a hot tub. You can wear the transmitter to a depth of 2.4 metres for up to 30 minutes.

If you disconnect from your insulin pump and your transmitter goes out of range for longer than 40 minutes (separated by more than 2 metres or 6 feet), only the last 40 minutes will be re-populated. Reports will have a "data gap" with missing information during this time period.

Calibrating GuardianLink®

Why do I have to calibrate my system?

Calibrating your system is like setting the time on your watch and adjusting it occasionally to make sure it’s still showing the correct time. To initialise a glucose sensor, you need to enter a meter reading to give the system a starting point. You will then need to enter at least two meter readings a day – once every 12 hours. This aligns the glucose sensor with the meter so that CGM readings are representative of your blood glucose (BG) level.

How often do I have to calibrate the MiniMed® Veo™ insulin pump?

Calibration is only necessary when you are using the CGM function of your insulin pump. The MiniMed® Veo™ insulin pump must be calibrated a minimum of twice a day (once every 12 hours) by entering a fingerstick value into the insulin pump. However, for best results, you can calibrate 3 to 4 times per day, with the calibrations spread throughout the day at periods when glucose is not changing rapidly. This will allow more accurate glucose detection at all levels.

How often do I have to calibrate the MiniMed® 640G insulin pump?

Calibration is only necessary when you are using the CGM function of your insulin pump. The MiniMed 640G insulin pump must be calibrated a minimum of twice a day (once every 12 hours) by entering a fingerstick value into the insulin pump. Follow these guidelines for best calibration results:

  • Spread out your calibrations throughout the day. To optimise sensor accuracy, calibrate 3 to 4 times a day.
  • Although you can calibrate any time during any rate of change, calibrating with two up or down arrows may temporarily decrease accuracy until the next calibration.
  • Enter your blood glucose (BG) meter reading into the pump immediately after testing your BG.
  • Your BG meter reading is only valid for 12 minutes; do not wait to enter it later.
  • Always use clean, dry fingers when you test your BG levels.
  • Use only your fingertips when obtaining blood samples for calibration.
  • If your BG meter readings are significantly different than your sensor glucose readings, you need to wash your hands and calibrate again.

When should I calibrate the MiniMed® Veo™ insulin pump?

It is best to calibrate when your blood glucose is not changing rapidly. We recommend that you calibrate on a routine schedule, for instance when you first wake up, before a meal, or before your bedtime snack. Try to find a time during the day when your blood sugar is stable as it is important to calibrate when glucose values are not changing rapidly. For example, glucose is more stable before a meal; do not calibrate after a meal, because it is more likely that glucose will change rapidly to adjust for the food being digested.

When should I calibrate the MiniMed® 640G insulin pump?

Two hours after starting a new sensor, do your first sensor calibration. Your pump sends a “CALIBRATE NOW” alert. Your first sensor glucose reading appears about 10 to 15 minutes after you calibrate.

Six hours after your first calibration, do your second sensor calibration. A “CALIBRATE NOW” alert appears, and your pump stops calculating your sensor glucose (SG) values. When you receive a “CALIBRATE NOW” alert, it takes about 15 minutes after you calibrate to receive SG values again

After you do your 2nd calibration, you need to calibrate at least every 12 hours. If you do not calibrate for more than 12 hours, a “CALIBRATE NOW” alert appears. It takes about 15 minutes after you calibrate to receive SG values again.

Follow these handy guidelines for best calibration results:

  • Spread out your calibrations throughout the day. To optimise sensor accuracy, calibrate 3 to 4 times a day.
  • Although you can calibrate any time during any rate of change, calibrating with 2 up or down arrows may temporarily decrease accuracy until the next calibration.
  • Enter your blood glucose (BG) meter reading into the pump immediately after testing your BG.
  • Your BG meter reading is only valid for 12 minutes; do not wait to enter it later.
  • Always use clean, dry fingers when you test your blood glucose levels.
  • Use only your fingertips when obtaining blood samples for calibration.
  • If your BG meter readings are significantly different than your sensor glucose readings, you need to wash your hands and calibrate again.

The CGM readings do not match my meter readings. Should I be concerned about this?

Blood glucose (BG) meters take glucose readings from plasma blood whereas sensors take readings from interstitial fluid. Most of the time glucose travels first to your blood and then to your interstitial fluid. Because of how glucose travels, your BG meter readings and sensor glucose readings will rarely match exactly. This is quite normal. When using your technology, you should concentrate on trends and patterns instead of individual values.