Why sugar ages skin and blood vessels and what to do about it today
Sugar sticks to protein
There is always sugar in the blood, and the body is built from proteins. When they meet, sugar can bind to a protein and stay on it.
- A protein with this mark works worse than before
- The mark holds on very firmly
- These traces of sugar are called marks
Much like the crust on meat
The browned crust on roast meat forms in a similar way: heat makes sugar bind to protein.
- In a pan it takes minutes
- In the body it happens quietly, over years
Long-lived proteins suffer most
The body renews most proteins quickly. But some proteins work for years, and that is where the marks build up.
- Skin collagen: its elasticity
- Vessel wall proteins: their softness
- Lens proteins: the clarity of the eye
Why the marks matter
A mark does more than take up space. It latches onto a special receiver on the cell, which switches on inflammation that drags on for years.
- Tissue becomes stiffer
- Inflammation runs in the background
What helps today
In type 1 diabetes, people who kept sugar lower for years had fewer marks in the skin. So it makes sense to smooth out sugar rises.
- Walk for 10 minutes after a main meal
- Eat vegetables and protein first, carbohydrates later
- Build your plate from vegetables instead of grains and bread
- Eat heavily fried food less often
The news behind it all
One of the main marks was long thought impossible to remove. This year scientists built an enzyme that removes it and returns the protein to its former state.
- Marks became clearly fewer on skin and vessels of older donors
- The work was done in a lab, on donor tissue
- This enzyme has not been given to people yet
What it means for you today
The enzyme is not in pharmacies, but one thing is already clear: marks build up not in one organ but everywhere at once.
- Skin, vessels and eyes travel the same road
- So it makes sense to look at the whole person
- The clearest step today is keeping sugar steady
Important
If you measure your sugar, there are limits at which you need a doctor rather than your own decisions.
- Repeatedly below 3.0 mmol/L (54 mg/dL): see a doctor
- Repeatedly above 8.9 mmol/L (160 mg/dL): see a doctor
- With diabetes, targets follow your doctor's plan; below 3.0 mmol/L (54 mg/dL) always see a doctor
Important. Important: do not change prescribed treatment on your own.
Key points
Glycation is when sugar from the blood binds to proteins and leaves a chemical mark on them. The marks build up on the longest-lived proteins: in the skin, the blood vessel wall and the eye lens. One of the most common marks, carboxymethyl-lysine (CML), was long considered irreversible.
In 2026 a paper in Nature Communications reported that scientists had built an enzyme, CMLase, that removes this mark and restores the original amino acid, lysine. On tissue sections from older donors, staining for the mark was more than 70% weaker in the aorta and more than 55% weaker in the skin, one donor per tissue (Trabosh N Nat Commun 2026. PMID 42448719[1]). The experiments used donor tissue outside the body; the enzyme has not been given to people. Sugar, which takes part in forming the marks, can be kept steadier today.
| Step | How much | How it helps | What studies showed |
|---|---|---|---|
| Walk after meals | 10 minutes after each main meal | Glucose rises less after eating | 41 adults with type 2 diabetes: glucose rose 12% less than with one 30-minute walk a day, 22% less after dinner |
| Vegetables and protein first, carbohydrates later | Carbohydrates 15 minutes after vegetables and protein | Lower glucose after eating | 11 adults with type 2 diabetes, pilot trial: glucose at one hour 37% lower than when carbohydrates were eaten first |
| Heavily fried food less often | Not the basis of the menu | Fewer ready-made marks from food | 12 dietary interventions, 293 participants in total: with more marks in food, more marks in blood and a higher inflammation marker, TNF-α |
What glycation is
Proteins are the working parts of the body. Most are renewed quickly, but some last for years: collagen in skin and vessels, proteins of the lens. The longer a protein lives, the more sugar marks it collects. Chemists call them advanced glycation end products (AGEs).
A similar reaction gives roast meat its browned crust, except that in the oven it takes minutes and in the body it takes years.
Why the marks matter
Some marks cross-link collagen fibres, which contributes to the loss of elasticity. CML also binds to RAGE, the receptor for advanced glycation end products, on cells, which triggers chronic inflammation (Trabosh N Nat Commun 2026. PMID 42448719[1]). The marks build up not in one organ but in the skin, vessels, kidneys and eyes at once, so it makes sense to look at the whole person.
What the scientists did
The starting point was a natural enzyme, glycine oxidase. It was improved by directed evolution: more than 500 million variants were screened in all, and the final enzyme emerged over five rounds. The new enzyme oxidises CML and puts ordinary lysine back in place (Trabosh N Nat Commun 2026. PMID 42448719[1]).
| Material | What was measured | Result |
|---|---|---|
| Purified proteins in a test tube | CML mark (immunoassay, ELISA) | 52–97% less, depending on the protein |
| Lens, donor aged 64, soluble proteins | CML mark: mass spectrometry and ELISA | 45% and 78% less |
| Abdominal aorta, donor aged 75 | Section staining for CML | More than 70% weaker |
| Skin, donor aged 74 | Section staining for CML | More than 55% weaker, below the level in skin from a 31-year-old donor |
The authors explain the difference in the lens this way: ELISA sees marks on the protein surface, which the enzyme can reach more easily, while mass spectrometry counts all marks, including those buried inside.
Why steady glucose matters
The enzyme is not in the clinic; a clear step is not letting glucose stay high for long. In a study of 216 people with type 1 diabetes, after 5 years of intensive treatment the early mark fructose-lysine (measured as furosine) in skin collagen was 30–32% lower than with conventional treatment, CML was 9–13% lower, and collagen was less cross-linked (Monnier V M Diabetes 1999. PMID 10102706[2]).
What you can do today
Who should see a doctor first
Glucose: see a doctor if it is repeatedly below 3.0 mmol/L (54 mg/dL) or above 8.9 mmol/L (160 mg/dL). If you do not have diabetes, the same limits apply; with diabetes, targets are individual and set in your doctor's plan, and below 3.0 mmol/L (54 mg/dL) always means seeing a doctor.
Do not change prescribed diabetes treatment on your own. With heart disease or diabetes complications, talk to a doctor before starting new physical activity.
Bottom line
A mark long considered irreversible can be partly removed in the lab by an enzyme from older donors' tissue. This opens a new line of research. Steady glucose, a walk after meals and vegetables at the start of a meal are available today.
References
- Trabosh N Nat Commun 2026. PMID 42448719
- Monnier V M Diabetes 1999. PMID 10102706
- Reynolds A N Diabetologia 2016. PMID 27747394
- Shukla A P Diabetes Care 2015. PMID 26106234
- Clarke R E Nutrients 2016. PMID 26938557
Key facts
- Glycation: sugar binds to a protein and leaves a chemical mark on it. Marks build up most on long-lived proteins of the skin, blood vessels and eye lens (Trabosh N Nat Commun 2026. PMID 42448719).
- The enzyme CMLase removes the mark carboxymethyl-lysine (CML) and restores the original amino acid, lysine. On tissue sections from older donors, staining for the mark was more than 70% weaker in the aorta (one donor, aged 75) and more than 55% weaker in the skin (one donor, aged 74) (Trabosh N Nat Commun 2026. PMID 42448719).
- This was laboratory work on purified proteins and donor tissue outside the body. The enzyme has not been given to people and cannot be used yet.
- Walking for 10 minutes after each main meal: in 41 adults with type 2 diabetes, glucose rose 12% less after meals than with one 30-minute walk a day, and 22% less after dinner (Reynolds A N Diabetologia 2016. PMID 27747394).
- See a doctor if glucose is repeatedly below 3.0 mmol/L (54 mg/dL) or above 8.9 mmol/L (160 mg/dL). If you do not have diabetes, the same limits apply; with diabetes, targets are individual and set in your doctor's plan, and below 3.0 mmol/L (54 mg/dL) always means seeing a doctor.
