A Potential Pitfall in Detection of Diabetes Mellitus Non-invasively Using the Second-Derivative of Photoplethysmography: Coexisting Hypertension May Blunt the Distinctive Difference in Early Negative to Initial Positive Wave Ratio (b/a) Between People With and Without Diabetes https://www.medrxiv.org/content/10.1101/2022.12.17.22283608