The purpose of this study was to determine if NO blood concentrations increased acutely following an 8-week course of pulsed infrared light therapy (PILT) which could be linked to an improvement in peripheral protective sensation (PPS) in patients who have profound chronic diabetic peripheral neuropathy. A total of 22 subjects with the diagnosis of type 1 (N = 2) or type 2 (N = 20) diabetes participated in the study. PILT was administered to one foot chosen at random with the other foot serving as a within-subject control (no treatment). Patients underwent 24 treatments (3 times/week, for 8 weeks) for 30 min per treatment. Venous blood samples were taken during the last 5 min of treatment from veins in the dorsum of the control and experimental feet and were later analyzed for NO concentration. Contrary to the popular supposition, PILT treatments actually resulted in a significantly (P < 0.05) decreased concentration of NO. Additionally, there were no significant differences between the treated and untreated feet. Since in individuals where PILT has significantly improved PPS, PILT did not stimulate an increased NO content in the blood, it appears that infrared light improves peripheral protective sensation in patients by a mechanism other than an increased NO production.

Pulsed infrared light therapy (PILT) has been shown to increase peripheral sensation in diabetic patients with diabetic peripheral neuropathy (DPN). However, most studies last for very short periods, with the subjects receiving only 6-20 treatments. The purpose of this study was to evaluate the effectiveness of an eight-week course of PILT in reversing long-standing, profound DPN in patients with type 1 and type 2 diabetes. Twenty-two subjects with a diagnosis of type 1 (n=2) or type 2 (n=20) diabetes participated in the study. PILT was administered to one foot chosen at random with the other foot serving as a within-subject control (no treatment). Patients underwent 24 treatments (3 times/week, for eight weeks) for 30 min per treatment. Changes in peripheral protective sensation (PPS) were measured using Semmes-Weinstein monofilaments (SWM) ranging from 3.7 to 6.48. PILT improved PPS even in patients with long-standing chronic neuropathies whose initial pre-study sensation was not measurable with a 200-g SWM. PILT significantly improves PPS. While the exact mechanism of action is not understood, infrared light may improve peripheral neuropathies by improving foot perfusion by stimulating nitric oxide production.