Supplemental Carnitine May Be Helpful in Diabetic Neuropathy

Laurie Barclay, MD

January 03, 2005

Jan. 3, 2005 — Supplemental carnitine can improve pain associated with chronic diabetic peripheral neuropathy (DPN), as well as vibratory perception and nerve regeneration, according to the results of two randomized, placebo-controlled trials published in the January issue of Diabetes Care.

“Acetyl-L-carnitine (ALC) is deficient in diabetes,” write Anders A.F. Sima, MD, PhD, from Wayne State University in Detroit, Michigan, and colleagues from The Acetyl-L-Carnitine Study Group. “In preclinical studies, substitution with ALC corrects perturbations of neural Na+/K+-ATPase, myoinositol, nitric oxide (NO), prostaglandins, and lipid peroxidation, all of which play important early pathogenetic roles in DPN.”

The investigators evaluated frozen databases from two 52-week trials testing two doses of ALC, 500 and 1,000 mg/day three times daily, in diabetic neuropathy. The 1,257 intention-to-treat patients consisted of 93% of enrolled patients. Primary outcomes were sural nerve morphometry, nerve conduction velocities, vibration perception thresholds, clinical symptom scores, and a visual analogue scale for the most bothersome symptom, typically pain. Both studies were evaluated together as well as separately.

Compared with placebo, ALC was associated with significant improvements in sural nerve fiber numbers and regenerating nerve fiber clusters. Although vibration perception improved with ALC in both studies, nerve conduction velocities and amplitudes did not improve.

Pain as the most bothersome symptom significantly improved with ALC in one study, and in the combined cohort receiving 1,000 mg ALC. In a subgroup (27%) of patients who reported that pain was the most bothersome symptom at baseline, 1,000 mg ALC tid for 52 weeks significantly improved pain, with symptomatic relief noted as early as 26 weeks. Pain relief was more pronounced in patients with type 2 diabetes of short duration, suboptimal hyperglycemic control and adequate treatment compliance.

“These studies demonstrate that ALC treatment is efficacious in alleviating symptoms, particularly pain, and improves nerve fiber regeneration and vibration perception in patients with established diabetic neuropathy,” the authors write. “To explore the full effect of ALC on DPN, longer trials initiated at an earlier stage of DPN need to be conducted.”

Dr. Sima is a consultant to Sigma-Tau Research.

Diabetes Care. 2005; 28:96-101

Reviewed by Gary D. Vogin, MD

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