Exercise training can modify the natural history of diabetic peripheral neuropathy

Abstract

Background

Diabetes is the most important cause of peripheral neuropathy (DPN). No definitive treatment for DPN has been established, and very few data on the role of exercise training on DPN have been reported.

Aim of the study

We sought to examine the effects of long-term exercise training on the development of DPN in both Types 1 and 2 diabetic patients.

Participants and methods

Seventy-eight diabetic patients without signs and symptoms of peripheral DPN were enrolled, randomized, and subdivided in two groups: 31 diabetic participants [15 f, 16 m; 49±15.5 years old; body mass index (BMI)=27.9±4.7], who performed a prescribed and supervised 4 h/week brisk walking on a treadmill at 50% to 85% of the heart rate reserve (exercise group: EXE), and a control group of 47 diabetic participants (CON; 24 f, 23 m; 52.9±13.4 years old; BMI=30.9±8.4). Vibration perception threshold (VPT), nerve distal latency (DL), nerve conduction velocity (NCV), and nerve action potential amplitude (NAPA) in the lower limbs were measured.

Results

We found significant differences on Δ (delta) in NCV for both peroneal and sural motor nerve between the EXE and CON groups during the study period (P<.001, for both). The percentage of diabetic patients that developed motor neuropathy and sensory neuropathy during the 4 years of the study was significantly higher in the CON than the EXE group (17% vs. 0.0%, P<.05, and 29.8% vs. 6.45%, P<.05, respectively). In addition, the percentage of diabetic patients who developed increased VPT (25 V) during the study was significantly higher in the CON than the EXE group (21.3% vs. 12.9%, P<.05). Change on Hallux VPT from baseline to the end of the study was significantly different between the EXE and CON groups (P<.05); no significant change in Malleolus VPT between the two groups occurred.

Conclusions

This study suggests, for the first time, that long-term aerobic exercise training can prevent the onset or modify the natural history of DPN.

Introduction

Diabetic peripheral neuropathy (DPN) is a common complication and quality-of-life damaging factor in diabetic patients (Boulton et al., 2004, Poncelet, 2003) and a leading cause of nontraumatic foot amputation (Boulton, 1998). Metabolic and vascular factors seem to be involved in the pathogenesis of DPN. Distal symmetric polyneuropathy is the most common form of DPN, involving usually both small and large nerve fibers (Boulton et al., 2004). Small nerve fiber neuropathies occur early in the course of diabetes and frequently develop with no objective signs or electrophysiologic evidence of nerve damage (Vinik, Erbas, Stansberry, & Pittenger, 2001). Although no definitive treatment for DPN has been established yet, several studies have shown that intensive therapy and optimal glycemic control can significantly reduce DPN (Azad et al., 1999, Dahl-Jorgensen et al., 1986, DCCT Research Group, 1995). Promising treatment for DPN include metabolic treatments, autoimmune therapies, and nerve growth factors (Vinik, 1999). Recent studies suggested that aerobic physical activity, alone or in combination with resistance exercise, may be an effective therapeutic modality for Type 2 diabetes (Castaneda et al., 2002, Dunston et al., 2002, Maiorana et al., 2002). The beneficial effects of a regular exercise on glycemic control, insulin sensitivity, lipid abnormalities, and hypertension in diabetic patients have been previously described (Balducci et al., 2004, Goldhaber-Fiebert et al., 2003).

Nevertheless, very few data on the effectiveness of exercise treatment on DPN have been reported (Richardson et al., 2001, Tesfaye et al., 1992). Prescribed and supervised long-term exercise programs may influence neuromuscular parameters in diabetic patients, thereby inducing adaptive changes in the neuromuscular system in response to exercise training.

In this study, we sought to examine the effects of a long-term exercise training on the development of peripheral neuropathy in both Types 1 and 2 diabetic patients.