Conditions that affect this writer, such as type 1 diabetes, require blood glucose levels to be checked many times every day. Usually, it involves pricking a finger with a lancet and putting a drop of blood in a glucose meter, a process that causes marks, hardens the skin and can be awkward.

Alternatively, glucose monitors are constant (CGMs). A flexible, wire-like needle that is fired into the skin is contained in these small devices. They stay on a carrier for about 10 days, sending blood glucose data every few minutes to a smartphone or smartwatch. When their blood glucose levels go dangerously low or high, while being much more convenient than finger pricking, CGMs are able to warn diabetics. But the need for them to be replaced several times a month means that they are expensive. Also, CGMs are easy to knock off the skin, can be very itchy, and can bleed sometimes.

Korean media claim that both Samsung and Apple’s next smartwatches will feature optical glucose monitors, which work to continuously measure levels by shining a light through the skin. Apple reportedly hired a team of biomechanical engineers to work on the feature in 2017, while Samsung last year developed a method of glucose monitoring called Raman spectroscopy that uses lasers to identify chemical compositions.

These features sound amazing on a personal level, but their appeal to diabetics will depend on the accuracy. Even invasive CGMs, which measure the glucose in the fluid surrounding the cells of a body, called interstitial fluid, are not always 100% correct, so it is difficult to imagine an optical sensor being as precise as finger pricking, but hopefully here.

It is expected that the Apple Watch 7 and subsequent Galaxy smartwatches will arrive later this year.