Table 2.

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

TrialDesignNumber R/CDoseDurationOutcome*
Ziegler et al,25 199524R,DB,PL328/260100, 600, or 1,200 mg qd parenteral ALA3 wkSignificant improvements  HPAL—600/1,200  (−1.4/−1.2 vs −0.5)
 NDS—1,200 (−1.8 vs −1.0)
 PGE—600 (76% vs 46%)
Not significant
 HPAL—100; NDS—100/600
Reljanovic et al,26R,DB,PL299/169/65600 or 1,200 mg qd2 ySignificant 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 199924R,DB,PL503/377
  1. 600 mg qd parenteral ALA (3 wk) then 1,800 mg qd oral ALA (6 mo) OR

  2. 600 mg qd parenteral ALA (3 wk) then oral placebo (6 mo) OR

  3. Parenteral placebo (3 wk) then oral placebo (6 mo)

6 moSignificant 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,28R,DB,PL24/221,800 mg qd oral ALA3 wkSignificant improvements
 1999 TSS (−3.8 vs −1.9)
 NDS (−0.3 vs 0.2)
Not significant
  • 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.