flash glucose monitoring revolution: the Sat Nav journey

Abstract

I am setting readers a challenge (Figures 1 and 2). I would like you to drive to Park Row in Leeds, a place you have not visited before. To get there you can drive your car and use your satellite navigation (Sat Nav) system. However, you can only look at your Sat Nav system on four occasions during your whole journey. Are you feeling uncomfortable? No wonder. But this is essentially what we have been asking people with diabetes to do for decades when it comes to glucose monitoring. Asking people with diabetes to check their blood glucose only before meals and before bed provides very limited information about what is happening to glucose levels in between meals and overnight. What would be preferable, of course, is the ability to see the glucose data across the full day, on demand, to check how the journey is going and, most importantly, to arrive safely at the desired destination.In 2014 the Abbott FreeStyle Libre device became available in the UK, allowing people with diabetes to monitor their glucose levels continuously. The Freestyle Libre flash glucose monitoring device is an arm-worn glucose sensor, the first two versions of which were the size of a £2 coin. The device reads glucose data every minute and transfers this information to a mobile phone app. The person with diabetes can then access their glucose data by scanning their phone over the sensor or, for those without a smartphone, there is a reader which can be used for scanning the sensor and doing glucose checks.The Impact flash glucose monitoring randomised controlled trial in 2014 demonstrated that the use of flash glucose monitoring in people with well controlled T1DM resulted in a 38% reduction in hypoglycaemia. 1 Interestingly, this reduction in hypoglycaemia occurred after the first fortnight of use, even though the users had no instructions on how to respond to their glucose data. This may initially seem surprising but viewing the data from the device shown in figure 3 makes clear how intuitive it can be for people with dia-betes to understand and respond to their glucose levels. For example, in the UK to be safe to drive a car in accordance with the DVLA regulations, your glucose must be above 5.0 mmol/L. 2 In the finger prick example in Figure 3 the glucose reading is 5.3mmol/L, implying that the individual would meet the criteria for safe driving. In the second example with a reading of 5.3mmol/L and a straight across arrow, indicating a steady glucose profile, again this would be reassuring for driving. In the third example with a reading of 5.3mmol/L and a downwards arrow indicating a rapidly reducing glucose level, it is clear that the person would need to take extra rescue carbohydrates to avert the risk of hypoglycaemia.