Chronic low-grade inflammation is a subtle, long-lasting activation of the immune system, with no infection or injury, that is associated with cardiovascular and metabolic diseases. Two blood markers reflect it: high-sensitivity C-reactive protein (hs-CRP), measured routinely, and GlycA, a nuclear magnetic resonance signal that is more stable over time. Neither makes a diagnosis.
What is chronic low-grade inflammation?
Inflammation is first and foremost a useful response: faced with an infection or an injury, the immune system mobilizes cells and proteins, then switches off once repair is complete. Chronic low-grade inflammation is different: a modest but persistent activation, with no visible cause, that lasts for months or years. It cannot be felt; it can only be measured.
A review published in Nature Medicine in 2019 by Furman and colleagues shows that this chronic systemic inflammation contributes to the development of cardiovascular disease, cancer, diabetes, chronic kidney disease, nonalcoholic fatty liver disease, and autoimmune and neurodegenerative diseases. The authors identify its drivers: physical inactivity, an unbalanced diet and obesity, lack of sleep, psychological stress, chronic infections and aging itself, a phenomenon sometimes called “inflammaging.”
Adipose tissue plays a central role: Inserm, the French National Institute of Health and Medical Research, notes that “one of the major abnormalities of adipose tissue associated with obesity is inflammation,” and that overweight and obesity are thought to be responsible for 44% of cases of type 2 diabetes and 23% of cases of heart disease. The gut microbiota is also involved: a high-fat diet increases the proportion of Gram-negative bacteria and the passage of inflammatory bacterial fragments, according to Inserm’s report on the microbiota.
How is inflammation measured: high-sensitivity CRP, GlycA and other markers?
The reference measurement in routine practice is C-reactive protein (CRP), produced by the liver in response to inflammatory signals. The high-sensitivity assay (hs-CRP) detects low concentrations, in the range that matters for prevention. A joint scientific statement from the American Heart Association and the Centers for Disease Control published in 2003 proposed three categories of relative cardiovascular risk based on hs-CRP: below 1 mg/L, between 1 and 3 mg/L, and above 3 mg/L.
Other markers (fibrinogen, interleukin-6) are used mainly in research; GlycA, measured by NMR, is the most recent to be included in prevention check-ups.
| High-sensitivity CRP | GlycA | |
|---|---|---|
| Nature | An acute-phase protein produced by the liver | An NMR signal combining the sugars (N-acetyl groups) carried by several acute-phase proteins |
| Technique | Immunoassay, any laboratory | NMR spectroscopy, as part of a metabolomic panel |
| Response to a minor infection | Strong and rapid, back to normal within a few days | Present but attenuated, because it is integrated across several proteins |
| Variability between measurements in the same person | High: 29.2% over five weeks (Otvos et al., 2015) | Low: 4.3% in the same study |
| Clinical experience | More than twenty years, published risk categories | A decade, associations validated in large cohorts; no consensus threshold |
| Availability | Reimbursed with a prescription | Not available on its own; included in NMR panels |
What exactly does GlycA measure?
GlycA (for “glycoprotein acetyls”) is not a molecule but a signal: NMR detects the N-acetyl groups carried by the sugars attached to several circulating glycoproteins. Otvos and colleagues showed in 2015 in Clinical Chemistry that this signal comes mainly from five acute-phase proteins, α1-acid glycoprotein, haptoglobin, α1-antitrypsin, α1-antichymotrypsin and transferrin, whose concentrations and glycosylation increase with inflammation. GlycA correlates with hs-CRP (r = 0.56), fibrinogen (r = 0.46) and interleukin-6 (r = 0.35): it measures the same phenomenon from a more integrated angle.
Its most interesting property is its stability. In the same study, within-person variability over five weeks was 4.3% for GlycA, compared with 29.2% for hs-CRP, 5.7% for cholesterol and 18.0% for triglycerides. Ritchie and colleagues, analyzing more than 10,000 people in Cell Systems in 2015, observed that GlycA levels remained stable within the same person for up to ten years, and that healthy people with high GlycA had elevated levels of many inflammatory cytokines and a higher long-term risk of severe infections, particularly sepsis and pneumonia. GlycA therefore reflects a chronic inflammatory state, whereas a single CRP result may reflect last week’s cold.
What does the literature, including UK Biobank, say about GlycA and disease risk?
The data are consistent but observational: GlycA is associated with the risk of many diseases, without it being possible to say that it causes them. Two lines of research shape what is known.
- Cardiovascular disease. In the Women’s Health Study, 27,491 initially healthy women were followed for a median of 17.2 years (1,648 cardiovascular events). Risk increased with GlycA: compared with the lowest quartile, the highest quartile had a hazard ratio of 1.64 in the main model. GlycA and hs-CRP were correlated (r = 0.61), and mutual adjustment attenuated both, a sign that they largely capture the same risk (Akinkuolie et al., JAHA, 2014).
- A wide range of diseases. In the atlas of the 249 NMR biomarkers measured in 118,461 UK Biobank participants, GlycA showed associations with about 32% of the more than 700 diseases studied, making it one of the most cross-cutting markers in the panel, alongside fatty acid ratios (Julkunen et al., Nature Communications, 2023). In the multi-disease prediction study conducted on 117,981 participants from the same cohort, GlycA stood out in particular for lung cancer and chronic obstructive pulmonary disease (Buergel et al., Nature Medicine, 2022).
These “broad-spectrum” associations should be read with caution: they indicate that a chronic inflammatory state accompanies, or precedes, many diseases, not that GlycA is a specific marker of them. This is what makes it interesting as an indicator of the underlying state in a panel of blood biomarkers, and of little use on its own for pointing to a specific disease.
What is the link between low-grade inflammation and cardiovascular and metabolic diseases?
Inflammation is involved at every stage of atherosclerosis: LDL that accumulates in the artery wall is chemically modified, which attracts macrophages and sustains a local reaction; the most inflammatory plaques are also the most unstable. Systemic inflammation measured in the blood partly reflects this activity, and partly that of adipose tissue and other organs. We describe the role of cholesterol-carrying particles in detail in the article on cholesterol and lipoproteins.
On the metabolic side, inflammation of adipose tissue disrupts the action of insulin: Inserm describes how, in obesity, “insulin, the hormone that regulates blood glucose levels, no longer works properly.” Low-grade inflammation, insulin resistance and the trajectory toward type 2 diabetes reinforce one another, a topic we cover in the article on blood sugar, HbA1c and prediabetes. The causal link has been tested: trials of targeted anti-inflammatory treatments in patients who had already had a heart attack reduced recurrences, although these treatments have no place in prevention for healthy people.
Finally, chronic inflammation is one of the components captured by biological age clocks and metabolomic age scores: see our article on metabolic age.
What reduces chronic inflammation?
What reduces chronic inflammation is, essentially, what reduces its causes: inactivity, excess body fat, an unbalanced diet, smoking, lack of sleep and chronic stress. None of these levers acts on inflammation alone; that is their value.
- Physical activity. Furman et al. point out that lack of exercise is a major cause of chronic disease and that exercise reduces inflammatory markers. A 2026 UK Biobank study (Miras-Moreno et al., Circulation: Genomic and Precision Medicine) identified the metabolomic signature of good cardiorespiratory fitness: it is characterized by downregulation of inflammatory pathways and metabolic dysfunction, and it is associated, over nine years, with a 39% to 54% lower risk of all-cause mortality and with less type 2 diabetes and cardiovascular disease. The French National Authority for Health (HAS) provides doctors with a guide to consultation and prescription of physical activity, updated in November 2025; the World Health Organization’s guidelines for adults cover weekly moderate endurance activity and muscle strengthening. See physical activity in prevention.
- Diet and weight. A Mediterranean-style diet rich in fiber, fruits and vegetables, legumes, unsaturated oils and fish, and cutting back on ultra-processed foods, are associated with lower inflammation, notably through the microbiota (Inserm). Losing weight in the case of excess body fat reduces inflammation of adipose tissue. Our guidance is in diet and nutrition in prevention.
- Smoking, sleep, stress. Quitting smoking, getting sufficient and regular sleep, and managing chronic stress are among the levers identified in the literature; Furman et al. show that partial sleep deprivation activates pro-inflammatory cellular pathways.
What are the limits of an inflammation marker?
An inflammation marker is nonspecific, sensitive to acute episodes and statistical: it tells you about an underlying state, not about a disease. Five limitations to keep in mind:
- It does not say where the inflammation comes from. Latent infection, periodontitis, adipose tissue, joint disease, smoking: the number is the same.
- A single measurement can be misleading. An hs-CRP measured during a cold, after an injury or after intense exercise reflects that episode; GlycA is more stable but not immune. Repeating the measurement later is the rule.
- There is no consensus threshold for GlycA. Associations are established by quartiles in cohorts; no guideline sets a “normal” value, and we do not give one.
- Association is not causation. A high marker accompanies a risk; lowering it artificially does not necessarily reduce that risk.
- It does not change a treatment decision on its own. European guidelines base the decision on overall risk as estimated by SCORE2; an inflammation marker can refine the discussion, but it does not replace it.
This is the framework in which we use it: one indicator of the underlying state among 249 measurements, interpreted with the person, in keeping with personalized health. The measurement technique is described in our article on NMR metabolomics.
Key takeaways
- Chronic low-grade inflammation is silent and associated with cardiovascular, metabolic, kidney and neurodegenerative diseases (Furman et al., 2019).
- High-sensitivity CRP is the routine marker; GlycA, measured by NMR, integrates several acute-phase proteins and varies much less from one measurement to the next (4.3% vs. 29.2%).
- GlycA is associated with cardiovascular risk (Women’s Health Study) and with nearly a third of the diseases studied in UK Biobank: an indicator of the underlying state, not a specific marker.
- Physical activity, a Mediterranean-style diet, weight, smoking, sleep and stress are the levers; no supplement has proven its worth in healthy people.
- An inflammation marker does not make a diagnosis and does not decide on a treatment by itself.
What Sokrate lets you do
The Sokrate service prepares your prevention check-up online with an adaptive questionnaire, after which a doctor writes and signs your Personalized Prevention Plan, sent to your regular doctor (médecin traitant) unless you object. The optional NMR metabolomic analysis of 249 biomarkers, performed on the Nightingale Health platform, includes GlycA; a doctor interprets it together with your lipoproteins, your blood sugar profile and your lifestyle habits, and explains what matters for you, without artificial thresholds. A coordinating nurse handles follow-up. Join the waitlist or find out how the pathway works.