High Dose Therapy With Alpha‐Lipoic Acid Improves Cutaneous Vasomotor Response In Patients With Diabetic Neuropathy

Abstract

The aim of our study was to evaluate the effect of alpha‐lipoic acid on the postocclusive hyperaemic response in type 2 diabetes (NIDDM) patients with diabetic peripheral neuropathy. Subjects: 36 NIDDM patients with diabetic peripheral neuropathy were divided in two groups according to the dosage of alpha‐lipoic acid: 18 patients received 600 mg (D1) and 18 patients received 1800 mg (D2) alpha‐lipoic acid orally for 4 weeks. 20 healthy subjects were selected as controls (C). Patient groups were matched for age, sex, body mass index and HbA1c. Subjects with peripheral vascular disease, hypertension, microalbuminuria and dyslipidemia were excluded. Methods: Before and after therapy we recorded changes in the cutaneous blood flow induced by 3 min arterial occlusion (cuff above the knee) on the pulp of the big toe using laser Doppler (LD) fluxmetry (PeriFlux 4001, Perimed). Basal LD flux (b‐LDF; PU), the percent increase of b‐LDF (ΔLDF; %) and the time to peak LD flux (t‐LDF; s) were calculated (PeriSoft program). Results: Before therapy b‐LDF on the pulp was significantly higher (mean ± SD; Mann‐Whitney U test) in diabetic patients (D1: 116.1 ± 47.4, D2: 99.8 ± 55.6 vs C: 58.5 ± 22.0 PU, p < 0.01), LDF was decreased in diabetic patients, and t‐LDF was significantly shorter in diabetic patients (D1: 22.8 ± 8.6, D2: 24.5 ± 7.1 vs C: 39.8 ± 9.7 s, p < 0.05) in comparison to controls. Oral therapy for 4 weeks with a high dose (1800 mg daily) of alpha‐lipoic acid restored ΔLDF (111.8 ± 44.9% vs 72.7 ± 11.0% before therapy, p < 0.05). Conclusion: Our results suggest that high dose of alpha‐lipoic acid improves responsiveness of cutaneous microvessels to arterial occlusion test in diabetic patients with peripheral neuropathy.