FRI606 Changes In The Pedal Microcirculation Of Diabetic Patients With Poor Glycemic Control Detected Using Non Invasive Optical Imaging
Authors: Kendra Bolakale-Rufai Ikeoluwapo , French Scott , Arias Juan C , Concha-Moore Kirsten , Tan Tze-Woei , Armstrong David G , Mazhar Amaan , Weinkauf Craig C 
Published: October 2023

Abstract
Disclosure: I.K. Bolakale-Rufai: None. S. French: None. J.C. Arias: None. K. Concha-Moore: None. T. Tan: None. D.G. Armstrong: None. A. Mazhar: Employee; Self; Modulim. C.C. Weinkauf: None.
Background: Microvascular disease (MVD) describes systemic changes in the small vessels (∼100 υm diameter) that impair tissue oxygenation and perfusion. Emerging evidence has shown that MVD (which is prevalent in diabetics) is clinically relevant as it synergistically acts with peripheral arterial disease to increase the risk of limb loss by 22.7-fold. Poor glycemic control has been linked to clinical microvascular disease (nephropathy and retinopathy) However, the direct impact of poor glycemic control on the microcirculation of the feet is unknown as there are currently no standardized non-invasive methods used clinically to assess and quantify MVD of the lower limbs. Spatial frequency domain imaging (SFDI) is a novel non-invasive optical technology that can detect and quantify microvascular disease of the foot by measuring the amount of hemoglobin(HbT1) in the capillaries of the superficial dermis up to 1-2mm deep and oxygenation (StO2) in the dermal micro-circulation. We hypothesize that poor glycemic control in DM affects pedal microcirculation and the changes can be detected using the SFDI technology. Methods: 307 patients (600 lower extremity limbs) were prospectively enrolled at a single institution, Banner University Medicine, Tucson, AZ from 2016- 2023. Diabetic patients were stratified into three groups based on their HbA1c level: ≤6.7%, 6.8-9.9%, and ≥10%. Mann U Whitney test and Spearman rank correlation were used in testing the association between HbA1C and SFDI-metrics with p&lt;.05 considered as statistical significance. Results: We included 230 lower limbs belonging to diabetic patients. The mean age of the patients was 61.7 years. Clinical neuropathy and retinopathy were found in 79% and 30.7% of patients, respectively. SFDI-derived biomarkers of microcirculation were compared among diabetics categorized by HbA1C levels. We observed a significant reduction in papillary dermal perfusion (HbT1) as the glycemic control (HbA1C) of the patients worsened (p&lt;0.001). Although tissue oxygenation (StO2) was not statistically different across diabetic groups, the St02/HbT1 ratio which represents the ratio of tissue oxygenation to perfusion, increased with elevated HbA1C levels. This indicated that poorly controlled diabetics had less oxygen being extracted from their poorly perfused micro-circulation. Conclusions: This study suggests that poor glycemic control directly affects the microcirculation of the feet in diabetic patients. The SFDI technology is a promising noninvasive tool to evaluate microvascular disease of the feet and potentially may be utilized clinically to stratify diabetic patients at risk for foot ulceration or limb loss based on glycemic control over time.
Presentation: Friday, June 16, 2023