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Carboxymethyllysine in Serum (CML)

Published: August 9, 2026Updated: August 16, 2026

This test measures a type of advanced glycation end product (AGE) found in your blood, which can help assess long-term exposure to sugar and inflammation.

Quick summary

["CML reflects chronic sugar exposure and oxidative stress in your blood."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
72469-0
Short code
RCS-4 5-carboxypentyl Ur Ql Cfm
Synonyms
RCS-4 5-carboxypentyl Ur Ql Cfm
Category
chemistry
Sample
urine
Container
Sterile urine container
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
confirm
Specimen volume
10 mL
Stability
Room temperature: 2h, Refrigerated: 24h, Frozen: 7d
Hemolysis max
0
Lipemia max
0
Icterus max
0
TAT
4–24 hours
Order
routine

What Is Carboxymethyllysine (CML)?

Carboxymethyllysine (CML) is a form of protein that develops when sugars in your blood react with proteins over time—a process called glycation. While natural in small amounts, higher levels may suggest prolonged high blood sugar or inflammation, which can be linked to conditions like diabetes or metabolic syndrome.

Why Might You Need This Test?

Your healthcare provider may order this test if you have diabetes, prediabetes, or other conditions affecting blood sugar control. It can also help monitor long-term damage to blood vessels or organs caused by chronic high sugar levels.

How Is the Test Performed?

A small blood sample is drawn from your arm, and the serum portion is tested using a specialized laboratory method to measure CML levels.

What Do Results Mean?

Results are not typically provided as a single reference range, as CML levels vary by individual and health status. Higher-than-expected levels may indicate increased glycation damage, while lower levels may suggest better metabolic control.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance: CML as a Biomarker

Short name

CML Serum

Frequently asked questions

Why was this test ordered?
Your doctor may have ordered this test to evaluate long-term sugar exposure, assess risks for complications like kidney disease or nerve damage, or monitor treatment effectiveness in conditions like diabetes.
What does a high CML level mean?
A high CML level may suggest chronic high blood sugar or oxidative stress, which can contribute to damage in blood vessels or organs. It doesn’t replace other tests like HbA1c but can provide additional context.
How often should I get this test?
Frequency depends on your health plan. If you have diabetes or metabolic concerns, your provider may recommend monitoring CML levels alongside other tests, such as HbA1c, every few years or as needed.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.

This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.

Medical Disclaimer

This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.

If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.

Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy