Quantitative Analysis of Heel Skin Microcirculation Using Laser Doppler Flowmetry and Tissue Spectrophotometry.

Objective: To examine perfusion changes in the heel skin of individuals with and without diabetes mellitus to understand how skin is pathologically affected by diabetes mellitus.

Methods: This case-control study was conducted at an academic hospital in Tuebingen, Germany. A total of 30 subjects were enrolled in the study: 15 with known type 2 diabetes mellitus and 15 without. Each subject was asked to lie in a supine position on a hard lateral transfer mat for 10 minutes.

Main Outcome Measures: Heel perfusion was quantitatively assessed directly after relief of pressure and after 3 and 6 minutes after relief of pressure using laser Doppler flowmetry and tissue spectrophotometry.

Main Results: Directly after relief of pressure, blood flow increased in the superficial skin layers (2 mm below the surface of the skin) in both groups. However, in deep skin layers (8 mm below the surface of the skin), blood flow increased in patients with diabetes mellitus and decreased in healthy patients. Oxygen saturation (SO2) was higher in healthy subjects directly after pressure relief.

Conclusions: The increase in blood flow in superficial skin layers indicates reactive hyperemia after exposure in both groups. The prolonged hyperemia in deep skin layers in patients with diabetes indicates increased tissue vulnerability. Despite the increase in blood flow in deep skin layers, the SO2 and thus supply of tissue in patients with diabetes were reduced.