Table 2.

Clinical Trials of Alpha-Lipoic Acid (ALA) and Diabetic Neuropathy.

Trial	Design	Number R/C	Dose	Duration	Outcome^*
Ziegler et al,25 199524	R,DB,PL	328/260	100, 600, or 1,200 mg qd parenteral ALA	3 wk	Significant improvements HPAL—600/1,200 (−1.4/−1.2 vs −0.5)
					HPAL
					NDS—1,200 (−1.8 vs −1.0)
					PGE—600 (76% vs 46%)
					Not significant
					HPAL—100; NDS—100/600
					PGE—100/1,200
Reljanovic et al,26	R,DB,PL	299/169/65^†	600 or 1,200 mg qd	2 y	Significant improvements
1999			oral ALA		Sural SNCV—600/1,200 (3.0/3.8 vs −0.1)
					Sural SNAP—600 (0.3 vs −0.7)
					Tibial MNCV—1,200 (1.2 vs −1.5)
					Not significant
					Sural SNAP—1,200; tibial MNCV—600
					Tibial MNDL—600/1,200; NDS—600/1,200
Ziegler et al,27 199924	R,DB,PL	503/377	600 mg qd parenteral ALA (3 wk) then 1,800 mg qd oral ALA (6 mo) OR 600 mg qd parenteral ALA (3 wk) then oral placebo (6 mo) OR Parenteral placebo (3 wk) then oral placebo (6 mo)	6 mo	Significant improvements NIS—3 wk (−4.3 vs −3.5) NIS-LL—3 wk (−3.3 vs −2.8)Not significant TSS—3 wk/6 mo NIS—6 mo; NIS-LL—6 mo
Ruhnau et al,28	R,DB,PL	24/22	1,800 mg qd oral ALA	3 wk	Significant improvements
1999					TSS (−3.8 vs −1.9)
					NDS (−0.3 vs 0.2)
					Not significant
					HPAL

R=randomized, DB=double-blind, PL = placebo-controlled, C=number of patients completing trial, HPAL=Hamburg pain adjective list, NDS=neuropathy disability score, PGE=physician’s global evaluation based on a rating scale of change in pain severity, SNCV=sensory nerve conduction velocity, SNAP=sensory nerve action potential, MNCV=motor nerve conduction velocity, MNDL=motor nerve distal latency, NIS=neuropathy impairment score, NIS-LL = neuropathy impairment score–lower limb, TSS=total symptom score.
* Numbers in parenthesis indicate significant difference compared with placebo in favor of ALA.
† Although 169 patients completed the trial, data from only 65 patients were used because of problems with data collection.