Can You Take Collagen If You Have Diabetes or Take Metformin?

No interaction between collagen and metformin has been documented: the BNF lists 19 metformin interactions, none of them collagen or protein.¹ Collagen is a protein, not a carbohydrate. In type 2 diabetes, one Chinese research group found lower fasting glucose and HbA1c after three months of collagen alongside usual medicines; no other group has repeated it.^{2, 3} Your pharmacist or diabetes team can check your prescriptions. This page sits beneath the Wellgard collagen guide, and the NHS metformin page asks you to "tell your doctor or pharmacist if you're taking any other medicines, herbal remedies, vitamins or supplements".⁴

Evidence at a glance

• Trials: three 2010 reports from one Chinese group in type 2 diabetes; a 2023 pooled analysis of 12 placebo-controlled trials in other groups found no change in glucose markers.^{2, 3, 5, 6}
• Largest trial reporting glucose: 100 adults with type 2 diabetes, 13 g a day of marine collagen peptides for three months (funding not stated).²
• Strongest measured outcome: 10 g of collagen peptides before a carbohydrate meal cut the glucose rise by about 37% in 30 adults (one test meal; manufacturer-funded).⁷
• Not tested: an interaction with metformin, collagen in type 1 diabetes, or use beyond three months in diabetes.

Sources checked on 13 October 2026.

Can you take collagen with metformin?

No interaction has been documented. The BNF interaction page for metformin, checked on 13 October 2026, lists 19 interactions, none of them collagen or protein, and the gliclazide page lists none either; a PubMed search the same day found no case report.¹ The NHS metformin page says, "You can eat as normal while taking metformin." It warns that "There are some medicines, herbal remedies and supplements that may not mix well with metformin", and names medicines such as diuretics as examples. It also says, "It's important to keep taking your medicine."⁴ Other medicines: can I take collagen with my medicines.

Does collagen raise blood sugar or spike insulin?

Protein raises insulin without raising blood sugar much, and collagen behaves like other proteins. In a 15-person trial supported by a collagen manufacturer, 15 g of collagen peptides a day for a week raised insulin by about 80% at its peak while blood glucose did not differ from placebo.⁸ In 10 men with type 2 diabetes, 50 g of beef protein could in theory have made 11 to 13 g of glucose; about 2 g reached the bloodstream.⁹

Over weeks, a Dutch university trial (its register lists support from a collagen manufacturer) gave 56 adults with overweight or obesity, none with diabetes, 10 g of collagen a day for four weeks, tracking glucose continuously: daytime glucose did not change, and small rises in glucose variability, after-meal glucose and fasting insulin were, in the authors' words, of "limited clinical relevance".¹⁰ A 2023 pooled analysis of 12 placebo-controlled trials found no change in glucose markers.⁶

What did the diabetes trials of collagen find?

One Chinese research group reported that 100 adults with type 2 diabetes who took 13 g a day of marine collagen peptides for three months, on top of their usual medicines, had lower fasting glucose and HbA1c than a placebo group; no other group has repeated it.^{2, 3} Its three 2010 reports may share participants, so they count as one source; funding is not stated.⁵ How high blood sugar affects skin collagen: does sugar damage collagen.

In a 30-person crossover trial funded by the ingredient's manufacturer, 10 g of collagen peptides taken half an hour before a carbohydrate meal reduced the rise in blood glucose by about 37%; in the 18 people with prediabetes the reduction was not statistically significant.⁷ Collagen has no authorised health claim in Great Britain, a statement about the register rather than a verdict on the trials, and none of this is a claim about diabetes.

Can diabetics take collagen, and is there a best one?

No collagen is made or tested for diabetes, so none is best for it. NICE advises clinicians to "Discourage adults with type 2 diabetes from using foods marketed specifically for people with diabetes"; what matters is the label.¹¹ Read the carbohydrate and "of which sugars" lines per serving, check flavoured formats for sweeteners or polyols, and count the calories: food labels count protein at 4 kcal per gram, so 10 g of collagen is about 40 kcal, all protein.¹² How much sugar is in collagen drinks and gummies gives the figures by format; for collagen tablets and capsules, compare grams per serving with the trial doses.

Collagen, protein and your kidneys with diabetes

In type 2 diabetes the NHS checks your "kidneys at least once a year".¹³ If your kidney team has set a protein target, collagen counts towards it like any protein; NICE advises against low-protein diets below "0.6 to 0.8 g/kg/day" in chronic kidney disease, so the target is individual. NICE also notes that eGFR, the kidney blood test result, "may be less reliable" in adults who "use protein supplements", so tell whoever checks yours that you take one.¹⁴ More: collagen and your kidneys; how much protein you need a day.

What should you ask your diabetes team or pharmacist?

If you use insulin or another medicine that can cause a hypo, NICE asks clinicians to "Individualise recommendations for carbohydrate and alcohol intake, and meal patterns", with reducing hypoglycaemia risk "a particular aim".¹¹ Ask your GP or diabetes nurse before changing what or when you eat, a protein drink included. The NHS lists "vitamin B12 deficiency, which can make you feel very tired" among metformin's common side effects (signs of vitamin B12 deficiency).⁴ For blends, see does glucosamine affect blood sugar. Suspected side effects of a medicine can be reported to the Yellow Card scheme.¹⁵

What we don't know

• No trial has studied an interaction between collagen and metformin (the Chinese abstracts do not name the medicines participants kept taking), and none has recruited people with type 1 diabetes.
• No independent group has repeated the Chinese diabetes trials.
• No collagen trial in diabetes has lasted longer than three months.
• Whether the glycine in collagen affects HbA1c has not been tested with collagen itself.

Frequently asked questions

Does collagen raise A1C?

No trial has found it: HbA1c fell in the Chinese diabetes reports and did not change in the Dutch trial.^{2, 10} Your own HbA1c, checked "every 3 to 6 months" in type 2 diabetes, shows your picture.¹³

Can type 1 diabetics take collagen?

No trial has tested collagen in type 1 diabetes, which the NHS calls "a problem with your immune system (autoimmune condition)".¹⁶ Ask your diabetes team, especially about insulin and meals; see collagen with an autoimmune condition.

Does the glycine in collagen lower HbA1c?

In one Mexican trial, 74 adults with type 2 diabetes given glycine for three months had lower HbA1c than on placebo.¹⁷ No trial has tested whether collagen does the same.

Is marine collagen better for diabetes?

No trial has compared marine, bovine or porcine collagen in diabetes, so none can be called better; the Chinese trials used fish collagen. Marine collagen is a fish product, which matters with a fish allergy.

Can I take collagen with metformin and a GLP-1 medicine?

None is documented: the BNF pages for metformin, semaglutide and tirzepatide list no collagen or protein interaction.¹ See collagen on tirzepatide and protein needs on tirzepatide.

Sources

1. NICE. BNF interaction pages for metformin (19), gliclazide (16), semaglutide (4) and tirzepatide (10), fetched 13 October 2026, none listing collagen or protein; PubMed search the same day. bnf.nice.org.uk.
2. Zhu CF, et al. Appl Physiol Nutr Metab, 2010. Randomised trial, 100 adults with type 2 diabetes, 3 months; funding not stated in the abstract. PubMed 21164551.
3. Zhu CF, et al. Am J Med Sci, 2010. Randomised placebo-controlled trial, 100 adults with type 2 diabetes and high blood pressure, 3 months; funding not stated in the abstract. PubMed 20739874.
4. NHS. Metformin. Page last reviewed 5 August 2026. nhs.uk.
5. Zhu CF, et al. Biomed Environ Sci, 2010. Randomised placebo-controlled trial, 200 adults with type 2 diabetes, 3 months; funding not stated in the abstract. PubMed 20514986.
6. Jalili Z, et al. Br J Nutr, 2023. Pooled analysis of 12 placebo-controlled trials; funding not stated in the abstract. PubMed 35658958.
7. Virgilio N, et al. Curr Dev Nutr, 2026. Randomised crossover, 30 adults (18 with prediabetes), single test meals; funded by the ingredient's manufacturer, four of eight authors its employees. PubMed 42699069.
8. Reynolds KM, et al. Br J Nutr, 2025. Randomised crossover, 15 women, 7 days; supported by a collagen manufacturer, two authors its employees. PubMed 40685650.
9. Gannon MC, et al. J Clin Endocrinol Metab, 2001. Randomised crossover, 10 men with type 2 diabetes, 8-hour tests; funding not stated in the abstract. PubMed 11238483.
10. Chavez-Alfaro MA, Mensink RP, Plat J. Clin Nutr, 2025. Randomised placebo-controlled trial, 56 adults without diabetes, 4 weeks; authors declared no conflicts; its trial register lists a collagen manufacturer's monetary or material support; full-text funding not checked. PubMed 39889494.
11. NICE. Type 2 diabetes in adults: management (NG28), dietary advice. Last updated 18 February 2026. nice.org.uk.
12. Regulation (EU) No 1169/2011, Annex XIV: energy conversion factors (assimilated GB law). legislation.gov.uk.
13. NHS. Treatment for type 2 diabetes. Page last reviewed 10 February 2025. nhs.uk.
14. NICE. Chronic kidney disease: assessment and management (NG203). Last updated 24 November 2021. nice.org.uk.
15. MHRA. Yellow Card scheme. yellowcard.mhra.gov.uk.
16. NHS. What is type 1 diabetes? Page last reviewed 31 October 2024. nhs.uk.
17. Cruz M, et al. J Endocrinol Invest, 2008. Randomised placebo-controlled trial, 74 adults with type 2 diabetes, 3 months; funding not checked. PubMed 18852529.

Spotted something out of date? Email support@wellgard.co.uk with the page address and the sentence.