L-Glutamine
EVIDENCE: WEAKAlso sold as: glutamine, L-glutamine powder
Glutamine is the most abundant amino acid in the blood. In people with type 2 diabetes, gram doses (15–30 g) raised the gut hormone GLP-1 and modestly lowered blood sugar in small short studies. Milligram amounts are far below anything studied.
Compiled by iSupplementReviews editorial team ·Researched 2026-10-16 · 3 sources
- Type
- Amino acid
- Studied dose
- 15–30 g per dose in glucose studies
- Best form
- L-glutamine powder
- Our rating
- WEAK — Mostly small, animal, or traditional evidence
What is L-glutamine?
L-glutamine is an amino acid the body makes and uses in large amounts, especially in the gut and immune cells. It is a common sports and gut-health supplement.
Other names and forms
Glutamine, L-glutamine. Usually sold as a powder because effective doses are measured in grams.
Where does L-glutamine come from?
Protein foods (meat, dairy, beans) and the body’s own production, mainly in muscle.
How does L-glutamine work in the body?
In the gut, glutamine stimulates cells that release GLP-1, a hormone that boosts insulin after meals. This effect has been shown with large oral doses.
What is L-glutamine claimed to do?
Support muscle recovery, gut lining, immunity and blood sugar.
What does the research show?
| Claim | Evidence | Dose studied | Verdict |
|---|---|---|---|
| GLP-1 and insulin response | Small human studies | 30 g single dose | Shown short-term |
| HbA1c in type 2 diabetes | Small crossover trial | 15 g twice daily, 4 weeks | Modest positive |
| Muscle recovery in healthy people | Mixed | Grams/day | Weak |
The GLP-1 effect
A 30 g oral dose raised GLP-1 and insulin in lean, obese and diabetic adults. Greenfield et al. (2009) showed the hormone response in a small acute study.
Four weeks in type 2 diabetes
Glutamine at 15 g twice a day modestly lowered HbA1c over 4 weeks. Samocha-Bonet et al. (2014) studied 13 people on metformin. Blood urea rose and there were mild plasma-volume changes. Mansour et al. (2020) also reported effects on post-meal glucose at gram doses.
What dose was studied?
| Goal | Dose | Duration |
|---|---|---|
| GLP-1 response | 30 g | Single dose |
| Glucose control | 15 g twice daily | 4 weeks |
Side effects
Bloating at high doses; raised blood urea in one diabetes study.
Drug interactions
- Anticonvulsant medicines: theoretical concern because glutamine is converted to glutamate (minor).
Who should not take L-glutamine?
People with advanced liver disease or kidney disease, unless a doctor advises it.
What the authorities say
Glutamine is a normal food component, and regulators treat moderate supplement intakes as safe. It is not approved for diabetes.
What to know about L-glutamine
Glutamine’s blood-sugar effects appear at doses of 15–30 grams. Milligram amounts are about a thousand times smaller than what was studied.
Frequently asked questions about L-Glutamine
Does glutamine lower blood sugar?
In small studies, yes, at gram doses. A 30 g oral dose raised GLP-1 and insulin, and 15 g twice daily for 4 weeks modestly lowered HbA1c in well-controlled type 2 diabetes.
How much glutamine is in food?
A typical diet provides several grams a day, mostly from protein. The body also makes its own.
Is glutamine safe?
It is generally well tolerated at several grams a day. In the 4-week diabetes study, blood urea rose and mild plasma-volume changes were seen.
References
- [1]Greenfield JR et al. — Oral glutamine increases circulating glucagon-like peptide 1, glucagon, and insulin concentrations in lean, obese, and type 2 diabetic subjects (Am J Clin Nutr, 2009)
- [2]Samocha-Bonet D et al. — Glycemic effects and safety of L-Glutamine supplementation with or without sitagliptin in type 2 diabetes patients: a randomized study (PLoS One, 2014)
- [3]Mansour A et al. — Postprandial glycemia and insulin secretion following glutamine administration: a randomized controlled trial (Int J Vitam Nutr Res, 2020)
Products we reviewed containing L-Glutamine
Based on recorded labels or seller-described formulas. Inclusion does not establish a match to the strains, preparations or amounts studied here; check each review's disclosure limits.