Orthostatic response in patients with type 2 diabetes mellitus evaluated through acceleration photoplethysmogram

Introduction: One of the striking complications of diabetes mellitus is arterial circulatory dysfunction. The 30:15 ratio is an orthostatic index commonly used to diagnose circulatory alterations in diabetic patients with a long evolution. Indices obtained from the second derivative of photoplethysmogram (SDPPG) or acceleration photoplethysmogram (APG) characterize arterial pathological changes. Aim: To compare the cardiovascular response of non-diabetic subjects to active standing versus that of type-2 diabetes (DM2) patients using APG indices. Methods: Digital photoplethysmography (PPG) was obtained from healthy subjects (n = 15, age ± SD, 44.6 ± 7.2 years) and DM2 patients (n = 15, age ± SD, 48.3 ± 7.9 years). The 30:15 ratio, b/a, d/a, and APG-AI, all APG-based, of the participants were calculated and compared at baseline, 15 and 30 s. Results: Comparison of the 30:15 ratios between groups did not show a significant difference. No significant differences were observed between the APG indices in the two groups in the baseline period. However, d/a decreased, and APG-AI increased significantly at beat 30 after active standing in non-diabetic subjects. Values of APG indices in DM2 patients did not show significant changes. Conclusion: The results suggest that APG indices could be used to detect early vascular dysfunctions in DM2 patients.