Living with diabetes requires enormous lifestyle changes. Once diagnosed, changes in food, exercise and medication habits are necessary to avoid complications. Keeping blood glucose under control can be challenging, with many factors such as stress, exercise, or a simple illness driving glucose levels out of control.
The most dangerous effect of short-term loss of blood sugar control is hypoglycemia, or simply hypos, which can lead to a loss of consciousness as a result of extremely low blood sugars. Symptoms often include confusion, feeling weak and a tingling sensation in the fingertips. On the other hand, continuous high blood glucose can have serious long-term consequences.
Blood glucose monitoring: The traditional way
The traditional way of measuring blood glucose involves a lancet (small needle) that pricks the fingertip, after which a small drop of blood is loaded onto a small machine, generating a reading (See figure 1). Doctors recommend testing blood sugars several times a day (ranging from 3-10 times), usually at least before every meal. However, despite being a relatively simple procedure, many patients do not check their blood sugars. Underlying reasons for this behaviour are psychologically complicated, but include a lack of motivation, perception issues, and inconvenience around needles and pain1. A study by Diabetes Self Management found that 21% of adults with Type 1 and 41% of insulin-dependent Type 2 diabetes never checked their blood sugar levels2.
This lack of control has lead to poor self-management of the condition, leading to complications that are not only detrimental to the patient, but also a huge cost burden on healthcare providers. The American Diabetes Association in 2013 estimated that the cost of diabetes in the US has risen to $245 billion, a 41% increase over a five-year period.3
Continuous glucose monitoring (CGM)
Players in the diabetes market have long identified the need for continuous glucose monitoring (CGM). In other words, a device that would continually monitor blood sugar levels and alert the patient when needed, and that would not require all the steps and appliances described in Figure 1.
One such example is Dexcom, which comprises of a small sensor that is placed just under the skin to monitor blood glucose levels, the direction it is moving in and how fast (See figure 2). Glucose data is then sent wirelessly every five minutes to the patient’s iPhone or any other receiver via Bluetooth®4. Glucose levels are then shown in vivid colors on the Dexcom App and the data is easily compiled and shared with healthcare professionals.
Apart from the Dexcom G5 mobile app that provides real-time glucose data and trends, Dexcom also offers CLARITY5, a diabetes management software that helps assess the user’s health by aggregating information on blood sugar highs, lows, daytime, nighttime and best day. The software also provides an estimate of A1C levels, which is a three-month average of blood glucose concentration (Figure 3).4 While Dexcom is widely used in the US, an equivalent device is offered by Abbott laboratories in Europe called the Freestyle Libre.6
Not only have the CGM devices such as Dexcom been instrumental in maintaining patient control over blood glucose levels, but they have also had profound impacts on two particular user groups: hypo unaware patients who have lost all sensations associated with hypos and simply cannot feel it anymore,7 and parents of children living with diabetes, for whom Dexcom has provided a great peace of mind, allowing them to monitor their children’s blood glucose remotely.
Drawbacks of current CGM devices
The primary drawback of both Dexcom and Freestyle Libre is invasiveness: both devices require that a sensor be placed under the skin, with the device being continuously attached to the user. This not only creates a risk of infection at the site of the sensor, but also harbors limitations on playing sports and clothing. Both devices have also caused allergic reactions in a significant number of users (personal communication, diabetes forums), are expensive, and need replacement every 1-2 weeks. Therefore, while CGM is always better than finger pricks, there is scope to look forward to yet more advanced monitoring systems that are less invasive.
Dare to dream: a world with non-invasive CGM?
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 Ong, W., Chua, S., Ng, C. Barriers and facilitators to self-monitoring of blood glucose in people with type 2 diabetes using insulin: a qualitative study (2014) Patient Prefer Adherence 8: 237–246
American Diabetes Association: http://www.diabetes.org/advocacy/news-events/cost-of-diabetes.html
 Dexcom CGM: http://www.dexcom.com/continuous-glucose-monitoring
 Dexcom CLARITY: http://www.dexcom.com/clarity
 Freestyle: https://www.myfreestyle.com/freestyle-freedom-lite-meter
 Hypo unawareness: http://www.diabetes.co.uk/hypo-unawareness.html