Abstract: This involves a non-invasive glucose measurement device and a process for determining blood glucose level in the human body using the device. In typical operation, the glucose measurement device is self-normalizing in that it does not employ an independent reference sample in its operation. The device uses attenuated total reflection (ATR) infrared spectroscopy. Preferably, the device is used on a fingertip and compares two specific regions of a measured infrared spectrum to determine the blood glucose level of the user. Clearly, this device is especially suitable for monitoring glucose levels in the human body, and is especially beneficial to users having diabetes mellitus. The device and procedure may be used for other analyte materials which exhibit unique mid-IR signatures of the type described herein and that are found in appropriate regions of the outer skin.