Last week, Google X publicly announced work on a glucose monitoring contact lens. The lens, ringed with tiny sensors, can read glucose levels from the fluids of the eye. Once perfected, technology like this could replace the continuous glucose monitors that are inserted under the skin via catheter.
Just because the technology was announced doesn’t mean it’s anywhere close to being available to purchase and use on a daily basis. Spokespeople at Google X suggest the device could be ready in about five years’ time. Before these lenses can safely go to market, the researchers will need to prove that they are as effective as fingersticks at determining the amount of glucose in the system at any given moment.
When asked if technology like this could be feasibly integrated into people’s lives once it’s perfected, Joslin’s Howard Wolpert, M.D., Investigator in the Section on Clinical, Behavioral and Outcomes Research and Director of the Joslin Institute for Technology Translation, said, “Ultimately yes, but there’s a long road ahead until this technology is likely to be established to be reliable, especially given lag issues.”
By lag issues, Dr. Wolpert means the difference between blood glucose levels and glucose levels in other bodily fluids, an important measure people with diabetes need to know to make decisions about insulin dosage. Under-the-skin sensors used in continuous glucose monitors measure the glucose found in interstitial fluid, or the fluids that surround the cells of your body. The glucose in these fluids typically lag behind the glucose in blood by anywhere between 5 to 15 minutes, which means the CGM could be almost a quarter of an hour behind in sensing blood glucose spikes or drops.
These contact lenses from Google would also have to contend with that kind of lag. In the absence of a fail-proof algorithm that precisely calculated an individual’s personal lag time, using this device could still require multiple fingersticks daily to ensure it was properly calibrated.
“Another limitation relates to the fact that contact lenses shouldn’t be worn while people are asleep and the overnight period is when people with type 1 diabetes are at most risk for hypoglycemia and when a continuous glucose monitor is of most benefit,” said Dr. Wolpert.
Of course, the researchers at Google understand they have a lot of work to do to make this monitor a reality for the 3 million Americans with type 1 diabetes. According to ABC News, “The company said these are ‘early days’ in its research. More would need to be known about the correlation between tear and blood glucose and what the lag time is in detection, as well as how the environment, such as heat and wind, can affect tears.”