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Apple, Google, and Samsung are exploring sensors for wearable devices that could measure glucose levels for diabetics, according to a Reuters report that cites people with knowledge of the companies' plans

The sensors would be non-invasive -- something that would appeal to people who must currently take blood samples to measure their glucose levels.

Samsung already offers wearable devices, including the company's Galaxy Gear smartwatch. Google, which is hosting its annual I/O developers conference this week, offers a platform called Google Wear that allows companies to run Android on their wearable devices. Apple, meanwhile, has been rumored to be working on an iWatch that has yet to be revealed.

Regardless of the stage their efforts thus far, the companies are all after a key feature: health monitoring. Countless reports over the last several months have suggested that all three firms are looking at ways to bundle sensors into wearable devices that would track key health data. All three firms have built some health features into their respective products, but have mainly stuck to simple items such as miles walked.

At Apple's own Worldwide Developers Conference earlier this month, the company unveiled a new slate of health options for developers, known as HealthKit. The feature set lets third-party app makers integrate their own health information with Apple's built-in Health app in iOS 8. All health-related information will be kept in a secure location for easy access by the user.

The trouble with glucose tracking is that it's difficult. Several companies have tried to track a person's blood sugar non-invasively, but nearly all have failed. The best way to check glucose is still to prick the skin and check the blood.

Google is on its way, though. The company has shown off a contact lens designed to measure glucose levels and tell people whether there is cause for concern. That product, however, is nowhere near launch, and Google hasn't said when it might be able to bring it to the market.

According to Reuters, Samsung is also getting closer to delivering glucose tracking and is working with several startups to build a "traffic light" system to alert people to their blood-sugar levels on future versions of the Galaxy Gear.

As for Apple? Details are scant. However, Reuters did say that its sources claim Apple will launch its long-awaited iWatch in October. Whether it will come with glucose tracking is unknown at this point.

CNET has contacted all three companies for comment. We will update this story when we have more information.