I've got a dubious watch bought from AliExpress that was even cheaper and that claims to monitor blood pressure as well as blood glucose levels, blood lipids and even uric acid levels (that's why I bought it as I get gout). It's obviously not going to be calibrated and accurate, and I did get my brother (who's Type 1 diabetic) to compare the watch readings with his own glucose measurement and it was over 10% out, but that could also be a timing issue as he had just recently eaten. Definitely not a device that you would use to determine insulin injections.