Protocol
Alpha-Lipoic Acid (racemic) 300–600 mg/day
Racemic (R plus S) alpha-lipoic acid is the form every cited trial gave: 300 mg a day in the one glycemic trial (Ansar 2011, PMID PubMed ID: the permanent number the US National Library of Medicine gives a published paper. Each one links to that paper's record on PubMed. 21666939; 57 adults, 8 weeks, fasting glucose and insulin resistance improved) and 600 mg or more in the neuropathy trials.
Grade C: human trials exist, but they are small, mixed or not yet repeated. This is not a finding that it does not work. How to read a grade →
Compare this record with another, side by side →
How this letter has changedLatest: October 2026 · Corrected.
The protocol was named R-ALA 300 to 600 mg fasted. Every cited trial gave racemic alpha-lipoic acid with no fasting instruction: Ansar et al. (Saudi Med J, 2011; PMID 21666939), 300 mg a day; Ziegler et al. (Diabetes Care, 2006; PMID 17065669, SYDNEY 2), 600 to 1,800 mg a day; Ziegler et al. (Diabetes Care, 2011; PMID 21775755, NATHAN 1), 600 mg a day for four years; and Han et al. (Eur J Endocrinol, 2012; PMID 22837391) pooled intravenous trials. The name now reads Alpha-Lipoic Acid (racemic) 300 to 600 mg/day, and the tracking note no longer asserts an R-form equivalence no trial measured. Letter unchanged at C; the review opened October is closed. Decided October 2026 by editor adjudication (Arnold Sandlow, D.C.).PMID 17065669 PMID 21666939 PMID 21775755 PMID 22837391
The R-ALA protocol held a B on the same bibliography as the supplement record: Ansar et al. (Saudi Med J, 2011; PMID 21666939), one 8-week glycemic trial of 57 adults; SYDNEY 2 (Ziegler et al., Diabetes Care, 2006; PMID 17065669); NATHAN 1 (Ziegler et al., Diabetes Care, 2011; PMID 21775755), null on its primary; and Han et al. (Eur J Endocrinol, 2012; PMID 22837391), a mostly intravenous pool. None used R-alpha-lipoic acid or fasted dosing. One positive glycemic trial without replication The same finding reproduced by a separate research group. A result seen once can be chance or bias; a replicated one is harder to explain away. is C. Moved October 2026 by editor adjudication; the name's R-form and fasted claims stay on the review roster.PMID 21666939 PMID 17065669 PMID 21775755 PMID 22837391
Every change to a letter on this site is dated and published. The full evidence log →
This protocol is alpha lipoic acid at 300 to 600 mg a day for blood sugar. It rests on one 8-week study of 57 adults with type 2 diabetes at 300 mg a day, which found better blood sugar and insulin use. No one has repeated it. The R form and taking it on an empty stomach were never tested in that study.
Racemic (R plus S) alpha-lipoic acid is the form every cited trial gave: 300 mg a day in the one glycemic trial (Ansar 2011, PMID 21666939; 57 adults, 8 weeks, fasting glucose and insulin resistance improved) and 600 mg or more in the neuropathy trials. No cited trial tested the R-form alone or dosing on an empty stomach, so the protocol is named for what was studied. One positive glycemic trial without replication is C.
Why this gradeGrade C, small or unreplicated trials. The reasoning, and what the grade does not cover.
Grade C on glucose and insulin resistance, resting on one 8-week trial in 57 adults with type 2 diabetes at 300 mg/day, form not stated (Ansar et al., 2011; PMID 21666939). One positive glycemic trial without replication is C.
WHAT THIS GRADE DOES NOT COVERthe R-form and dosing on an empty stomach, which no cited trial tested (the protocol was renamed to the racemic form studied in October 2026); and diabetic neuropathy, where the trials used racemic alpha-lipoic acid at 600 mg or more (SYDNEY 2, PMID 17065669; NATHAN 1, PMID 21775755) or intravenous dosing (PMID 22837391).
A grade describes the human evidence for a named use. It is not advice, and it is not a judgment on any individual prescription. How the letters are decided →
The evidence, in fullFour papers, each linked to its PubMed record.
Ansar et al. (Saudi Medical Journal, 2011; PMID 21666939): 8-week RCT Randomized controlled trial: people are assigned to the treatment or a comparison by chance, so the groups differ only in what they received. It is the design that can show cause and effect., 57 adults with type 2 diabetes, oral alpha-lipoic acid 300 mg/day, form not stated; fasting glucose and insulin resistance improved. Han et al. (European Journal of Endocrinology, 2012; PMID 22837391): meta-analysis A study that pools the numbers from several trials into one combined estimate. of randomized trials of INTRAVENOUS alpha-lipoic acid 300 to 600 mg/day in diabetic neuropathy; the authors rate the trial quality poor. Ziegler et al. (Diabetes Care, 2006; PMID 17065669, SYDNEY 2): 5-week RCT, oral RACEMIC alpha-lipoic acid 600, 1,200 or 1,800 mg once daily; neuropathy symptoms improved at every dose. Ziegler et al. (Diabetes Care, 2011; PMID 21775755, NATHAN 1): 4-year RCT, oral racemic alpha-lipoic acid 600 mg/day; primary composite endpoint The outcome a trial measures to decide whether the treatment worked, such as heart attacks, blood pressure or a symptom score. not different (P=0.105), serious adverse events 38.1 versus 28.0 percent. No cited trial used R-alpha-lipoic acid or a fasted protocol. Grade C: one positive short oral trial, one null long oral trial, and no trial of the R-form or of fasted dosing.
Fasting glucose and insulin at baseline and 12 weeks for metabolic applications. For neuropathy, use the Total Symptom Score (TSS) at baseline and 5 weeks: the IV diabetic neuropathy trials showed effects within 3-5 weeks. The trials gave racemic alpha-lipoic acid; no cited trial compared it with the R-form, so the record states no equivalence between them.
Evidence notes: not independently replicated, randomized trial, meta-analysis
Endpoint graded: Glucose and insulin resistance in type 2 diabetes (surrogate)
Last reviewed: July 2026
Educational use only · Not medical advice · EBL grades published human evidence and does not recommend treatment. Stopping a prescription is a decision for your physician.
Evidence Based Longevity, Inc. is owner-operated and edited by Arnold Sandlow, D.C., a California-licensed chiropractor. Evidence Based Longevity publishes in English only · Machine translations are not produced or reviewed by EBL for accuracy
© Evidence Based Longevity, Inc.. All rights reserved
These statements have not been evaluated by the Food and Drug Administration. Any grade on this page describes the strength of published human trial evidence in the populations studied. It is not a recommendation for any individual and is not medical advice. Starting, stopping or changing any supplement or medication is a decision for your physician.
How EBL searched for the trials (1 search)
The search that was run, what it returned, and what was left out and why, so the absence of evidence can be checked as well as its presence.
("alpha-lipoic acid"[tiab] OR "thioctic acid"[tiab]) AND (insulin resistance[tiab] OR insulin sensitivity[tiab] OR fasting glucose[tiab]) AND randomized controlled trial[pt] AND humans[mesh]Grades move when new trials publish. A free monthly email lists every grade EBL moved, with the reason and the trial behind it: the sign-up is on the Evidence Log →