Unfortunately - likely to be snake oil product
This link
https://blog.adafruit.com/2015/05/0...sive-glucose-meter-project-wearablewednesday/
Is to a do it yourself device using the same principles.
On that page there is a link to an online book covering research into this.
http://www.mendosa.com/The Pursuit of Noninvsive Glucose, Fourth Edition.pdf
Whilst a pulse oximeter has good clear science principles behind it (differing UV/Red light frequency profile between haemoglobin which has oxygen / and that which does not ) the evidence is pretty thin on this working for glucose concentration.