Non invasive measurement of blood glucose in diabetic patients by using (Near Infra Red-NIR) NIR- emitter and silicon photo detector with wave length of 100 to 1100 nm. The emitter is an 940nm IR LEDand the detector is a photodiode chip with 1100nm wave length. The emitter and the detector are built as a Glucometer which is integrated with a microprocessor and display and power supply, to make an instrument which has a window through which the NIR is emitted where the finger or any body part like earlobe, cheek, finger, wrist can be placed to measure the blood glucose levels. The instrument measures the absorbance of NIR in the blood and displays the readings on the display as ADC(analogue to digital values) which is computed to the blood glucose levels in Mg/dl. and displayed on the instrument or computer screen using proprietary software application.