Estimation of blood glucose by non-invasive infrared thermography for diagnosis of type 2 diabetes: an alternative for blood sample extraction.

The present study aims to estimate and validate the glycated haemoglobin (HbA(1c)) using non-contact infrared thermography. The diagnostic threshold was set as (HbA(1c)≥48 mmol/mol). The optimal regression model [r=0.643, p=0.000] was achieved from the significant variables correlating with the HbA(1c) and the validation was performed against the bio-chemical assay to indicate the sensitivity, specificity, positive predictive value, negative predictive value and with an accuracy of [90%, 55%, 65%, 85% and 72%] respectively. The non-invasive core body temperature measurement at the inner canthi of eye [r=-0.462, p<0.01] indicated negative correlation with HbA(1c), that signifies the early metabolic changes. In type 2 diabetes, the core body temperature decreases with a decrease in the body metabolism. Thereby, a truly non-invasive infrared thermography could be used for obtaining the accurate HbA(1c) with no blood sample extraction; further, it could be used as the preferred diagnostic tool for type 2 diabetes.