I recently got into a heated deabate with my gp regarding my Apple Watch which I use for various things and was told not to rely on them. After a lot of research I found that it had been verified as correct and approved by the NHS. I recently have been having tests for a high heart rate and every time the watch matched the doctors equipment. However Apple have stated that they are 3 years off getting a watch to work for diabetes. So if Apple can’t manage a diabetic watch yet I’m don’t think a watch under £20 is going to work