Flash glucose monitoring systems

Flash glucose monitoring systems (eg FreeStyle Libre) measure the glucose concentration in interstitial fluid every 15 minutes. To download the measurements, a reader or smart phone is swiped over the sensor; this should be done at least every 8 hours (three times a day) to give a continuous 24-hour assessment and to clear data from the sensor, which has limited storage capacity. The device does not require calibration with capillary (finger-prick) blood glucose concentration readings. However, during an episode of hypoglycaemia or hyperglycaemia, SMBG measurements are still needed to verify the readings because flash glucose monitoring systems do not detect rapid changes in blood glucose concentration and inaccuracy is likely in readings in the low or high blood glucose concentration ranges.

Unlike CGM systems, flash glucose monitoring cannot alert the user if their glucose concentration is becoming low or high, or transmit data to a CSII pump.

In patients with type 1 diabetes in whom glycaemic targets are achieved, flash glucose monitoring can reduce the time spent in hypoglycaemia without a deterioration in the glycaemic profile.

At the time of writing, the National Diabetes Services Scheme (NDSS) subsidises flash glucose monitoring equipment for:

• children and people younger than 21 years with type 1 diabetes
• children and people younger than 21 years with conditions very similar to type 1 diabetes who require insulin
• women with type 1 diabetes who are actively planning pregnancy, pregnant or immediately post-pregnancy
• people with type 1 diabetes aged 21 years or older who have concessional status.