Most systems show results instantly on a portable receiver which is about the size of a pager or iphone. Two companies Medtronic and Animas offers a sensor receiver integrated into a pump.
Common features include:
* a display of current glucose level
* a trend arrow indicating whether glucose is falling or rising
trend information e.g. a graph showing results over the last three, six or 24 hours
* alarms to indicate high or low glucose or rapid change. Some systems provide early warning alarms if glucose levels are likely to fall too high or low. Alarms can usually be set by the user at the level they want. There may be a choice of an audible or vibrating alarm ability to download data and view graphs and statistics.
There are currently 3 companies offering CGM systems in the UK:
* Abbott offer the freestyle navigator
* Advanced therapeutics offer the DEXCom seven plus as a stand-alone system or you can use the Animas VIBE pump which uses the very latest Dexcom sensor technology (G4 sensors).
* Medtronic offer the GUARDIAN, the iPro or CGM integrated into a Medtronic paradigm pump.
Bayer are currently developing a CGM system- but it is not yet available. OmniPod have development agreements in place with both Abbott Diabetes Care and DexCom, so Omnipods users may gave a choice in the future – but this is not yet the case. Gary Scheiner has a useful comparison of different CGM systems on the website integrated diabetes (It is written for a US audience so some details may not apply to the UK.)
Abbott Freestyle Navigator
The FreeStyle Navigator sensor system is a wireless, water resistant system. Users can get continuous glucose readings once every minute as long as the receiver is within 3 metres of the transmitter. (This can be helpful for children as the parent can have the receiver in the next room.
The sensors cost around £40 each. Each sensor can be worn for up to 5 days, though some report wearing them longer. The sensors have a shelf life of 18 months (without refrigeration).
The FreeStyle Navigator system also includes a built-in blood glucose meter . In contrast to the other systems the Freestyle Navigator uses disposable (rather than rechargeable) batteries.
You can read more about the freestyle navigator here
DexCom SEVENplus
The DEXCOM 7 + is a wireless, waterproof system. It has a large widescreen display. Unlike other CGM systems it is possible to calibrate the system even when glucose levels are changing rapidly.
Sensors are licensed to last 7 days, though some users report wearing them longer. The sensors cost £60 each. They have a shelf life of 6 months. Please be aware that products containing paracetamol (also known as acetaminophen) can adversely affect the accuracy of the Dexcom 7 +.
There is an option to record events that may affect your control(such as insulin, exercise, illness, food intake, etc.). The software can be used with a Mac or a PC. An example screenshot is shown below.
You can find information about the Dexcom7 from the UK distributors advanced therapeutics. If you want to try the Dexcom before committing yourself to buying it ask about their pre- sales trial option, which allows you to use the Dexcom for 2 weeks and return it if it does not suit you. (You have to pay the full amount which can be refunded and you pay the cost of any sensors you have used). Further details about the product itself are available from the US manufacturers Dexcom.
Dexcom has now developed G4 sensors – which can currently only be used with the ANIMAS vibe pump, and not with the SEVENplus receivers. It is expected that a new receiver will be developed.
Medtronic
Medtronic now offer the following CGM options:
* GUARDIAN realtime, a standalone device without pump
* CGM integrated into one of their paradigm pumps such as the VEO
Medtronic introduced a new sensor Enlite in April 2011. The sensor is a lot smaller than the previous one. It also has a new inserter – the inserter needle on the last one was pretty scary! Enlite sensors last 6 days, though many report wearing them for longer. They do not need to be refrigerated. The most important improvement – which seems to be backed up by reports from users – is that the sensors are much more accurate. Unfortunately these improvements come at a cost. The old sensors cost around £37 each when buying a box of 10, the new ones are £52 when buying 10.
Both systems allow you to upload your results to the web based Carelink system. This provides a wide range of reports and graphs to help you interpret your CGMS results and to identify how to improve your control. If you choose you can give health care professionals access to your results. An example report is shown below.
Medtronic also offer the iPRO which is intended for use by medical professionals.
You can find out more about Medtronic’s approach to glucose monitoring here.
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