We compare spectral analysis of photoplethysmography (PTG) with insulin resistance measured by the hyperinsulinemic euglycemic clamp (HEC) technique. Material and Method: A total of 100 nondiabetic subjects, 43 men and 57 women aged 20-63 years, 30 lean, 42 overweight and 28 obese were enrolled in the study. These patients underwent an examination with HEC, and an examination with the PTG spectral analysis and calculation of the PTG Total Power (PTG-TP). Receiver-operating characteristic (ROC) curves were constructed to determine the specificity and sensitivity of PTG-TP in the assessment of insulin resistance. Results: There is a moderate correlation between insulin sensitivity (M-value) and PTG-TP (r = -0.64, p < 0.0001). The ROC curves showed that the most relevant cutoff to the whole study group was a PTG-TP > 4062. This cut-off had a sensitivity = 95.7%, specificity = 84,4% and the area under the ROC curve (AUC) = 0.929 for identifying insulin resistance. All AUC ROC curve analysis were significant (p < 0.0001). Conclusion: The use of the PTG-TP marker measured from the PTG spectral analysis is a useful tool in screening and follow up of IR, especially in large-scale studies. (C) 2017 The Authors. Published by Elsevier Inc.311128133