1805-LB: Attenuation of Niacin-Induced Skin Flushing Response-A Potential Clinical Adjunctive Diagnostic Instrument for Diabetic Peripheral Neuropathy

Objectives: Explore the potential of using niacin-induced skin flushing response (NSFR) as a diagnostic method for diabetic peripheral neuropathy (DPN) based on the microangiopathic characteristics of DPN. Methods: This study involved 114 diabetic patients (51 with DPN, 59 without DPN, and 4 with an undetermined diagnosis) and 91 healthy controls(HC). DPN was assessed through clinical symptoms and/or signs, quantitative sensory tests, and electromyography. NSFR is detected using a modified 6-chamber sandwich patch and six different concentrations of aqueous methyl nicotinate (AMN). The sum of the 6 AMN concentrations' flushing area scores within 10 minutes after reaction were calculated and defined as the total NSFR score. Results: NSFR to gradient concentration stimulation of AMN is reduced and delayed in diabetes patients compared to HCs, and the total NSFR score was significantly decreased (6827.3 (5038.45) vs. 10680 (5060.2)mm2, P < 0.001). The decline in NSFR was more pronounced in diabetes patients with DPN compared to those without DPN (4517.9 (3909.3) vs. 8896.5 (5179.7)mm2, P < 0.001). The association between NSFR and diabetic neuropathy was further evaluated using a multinomial logistic regression model. After adjusting for covariates that might affect NSFR or neuropathy (including age, sex, diabetes duration, BMI, fasting C-peptide, and HbA1c), NSFR was still independently associated with diabetic neuropathy (odds ratio: 0.903 (95% CI: 0.843-0.968), P=0.004). The optimal cut-off point of total NSFR score to distinguish diabetic neuropathy from non-diabetic neuropathy was 8530mm2, with a sensitivity of 88.2% and a specificity of 49.2%. Conclusions: NSFR reduction is closely and independently associated with the existence of peripheral neuropathy in diabetic patients, and has great potential as an auxiliary tool in diagnosing diabetic peripheral neuropathy.