How to Read Your GlycanAge Result: A Guide to Interpreting the 5 Indexes

Your GlycanAge result is a measure of your immune system's biological age — specifically, how chronic inflammation (the slow, persistent kind that drives age-related disease) is aging you relative to your chronological age. The result is built from 29 different glycan structures attached to Immunoglobulin G (IgG) antibodies (the immune proteins that coat every cell in your body) grouped into five indexes that together reveal not only how fast you are aging, but why.

Want the full picture of what's behind your number? Read Biological Age Testing: The Complete Guide to Measuring How Fast You're Actually Aging for a deeper look.

What does the biological age number on my GlycanAge result mean?

Your GlycanAge biological age is a single number, between 20 and 80, that represents the overall level of background chronic inflammation contributing to your aging. It is not your chronological age, and it is not a disease diagnosis. It is a measure of where your immune system sits relative to the population of people your age: younger means less chronic inflammation, older means more.

Because GlycanAge measures IgG glycans, and IgG has a half-life of approximately 21 days, the result reflects consistent, sustained biological patterns rather than yesterday's choices. A single night of poor sleep or a glass of wine will not shift your result; what moves it is chronic behavior sustained over at least six weeks. That stability is what makes the number meaningful: it filters out noise and captures the biology that actually matters for long-term health.

"The most valuable thing about glycans is that they can be easily and reliably quantified — we get a drop of blood, and we can return a glycome composition. But more important than the number itself is the pace of change. If I shift to a healthier lifestyle, it goes down. It's responding to interventions — it can tell me whether what I'm doing is good or not."

— Prof. Gordan Lauc, Chief Scientific Officer, GlycanAge; Professor of Biochemistry and Molecular Biology, University of Zagreb

What are the five glycan indexes, and what does each one measure?

GlycanAge groups its 29 analyzed glycan structures into five indexes based on shared chemical and functional properties. There are three primary indexes — they have a clear pro- or anti-inflammatory function and directly drive the biological age calculation. The other two supportive indexes do not change in a predictable pattern with aging, but rather shift with inflammation and are associated with specific health areas.

Primary indexes:

• Glycan Shield measures the presence of sialic acid on IgG glycans and is anti-inflammatory. A low Glycan Shield score is a good indicator to check for vitamins, toxins, and nutrient deficiencies.
  
  

• Glycan Youth measures the presence of two galactose molecules on IgG glycans and is anti-inflammatory. It is called "Youth" because these structures are most abundant when we are young; their decline is associated with a higher risk of autoimmunity and is observed in older populations, people with higher BMI, cancer patients, and those with non-alcoholic fatty liver disease.
  
  

• Glycan Mature measures the absence of galactose and is pro-inflammatory. A high Glycan Mature score is associated with hormonal imbalance and is an indication to review a patient's hormonal balance.

Supportive indexes:

• Glycan Median measures the presence of one galactose. A low Glycan Median score is associated with cardiovascular health; when combined with a low Glycan Mature score, it can indicate cardiac health concerns.
  
  

• Glycan Bisection measures the presence of bisecting GlcNAc and is associated with lifestyle factors, specifically sleep, stress, and smoking.

What is the difference between primary and supportive glycan indexes?

Primary indexes, such as Glycan Shield, Glycan Youth, and Glycan Mature, change in a predictable, directional pattern as we age, which is why they are used to calculate the biological age number itself. Supportive indexes do not follow that predictable aging trajectory, but they do respond to inflammation and to specific conditions or lifestyle patterns, making them valuable for understanding what is driving a result.

In practice, this means a result where all three primary indexes look acceptable can still contain important information in the supportive indexes, and vice versa. The report is designed to surface both layers, with personalized insights indicating which indexes warrant the most attention for a specific individual.

How do I know if my glycan index scores are good or bad?

Each index is scored on a scale where a higher score indicates a greater abundance of glycans within that group. Because glycans can be either pro- or anti-inflammatory, a higher score is favorable for some indexes and unfavorable for others. Higher Glycan Shield and Glycan Youth scores are better — more anti-inflammatory activity. A higher Glycan Mature score is less favorable — more pro-inflammatory activity.

Your report places each index score within a range — optimal, average, or outside the expected range — relative to the reference population. This context is vital because chronic inflammation shifts at each life stage, meaning "normal" looks different in your 40s than it does in your 60s. The personalized insights section of the report identifies which indexes to prioritize for your specific result, so you are not left interpreting raw numbers without context.

Can my glycan indexes tell me what is causing my biological age to be higher than expected?

Yes, this is precisely what the indexes are designed to do. The biological age number tells you that chronic inflammation is accelerating your aging; the indexes tell you what is likely driving it. A high Glycan Mature score points toward hormonal factors. A low Glycan Shield score points toward nutritional deficiencies or toxin exposure. A low Glycan Youth score points toward autoimmune activity. A low Glycan Median score, particularly alongside a low Glycan Mature, points toward cardiovascular health.

This directionality is what makes GlycanAge actionable rather than merely informative. The indexes give clinicians and individuals a starting point for targeted intervention, whether that is reviewing hormone levels, investigating nutritional status, or adjusting lifestyle factors, rather than a single number with no clear path forward.

"There's no single biomarker that can function for everything, but glycans are predictive, they're responsive, they're stable. They are such a great indicator of inflammation and a very, very good biomarker of aging."

— Dr. Joseph Raffaele, Raffaele Medical, New York

Will my indexes change if I make lifestyle changes, and how quickly?

GlycanAge is uniquely responsive among aging biomarkers: because IgG glycans reflect sustained biological patterns rather than acute fluctuations, GlycanAge shows low intra-individual variability compared to epigenetic clocks, making genuine change easier to distinguish from measurement noise. Meaningful change requires consistent behavior maintained over at least six weeks, but how soon you should expect to see it depends on the type of intervention:

• Pharmaceutical or medical interventions (HRT, targeted metabolic treatments, biologics): changes in immune balance and glycan composition can be observed within 3–4 months. Retesting in this window allows for early assessment of response and protocol adjustments.
  
  

• Lifestyle-based interventions (diet, exercise, stress management, sleep improvement): glycan shifts occur more gradually, typically requiring 6–12 months to show measurable, sustained improvement.

This is why GlycanAge recommends retesting based on the type of change you've made, not a single fixed window. The second result, not the first, is where the real value lies: it shows whether a specific change has moved the biology that matters. Samples are analyzed in a CLIA-certified laboratory using capillary gel electrophoresis, ensuring the accuracy needed to detect genuine biological change.

What should I do after reviewing my glycan indexes?

Every GlycanAge result includes a 1:1 Result Interpretation Call with a longevity specialist who walks you through your biological age, each glycan index, the associated health areas, and a personalized action plan. The report also includes a summary of action steps and a recommendation on when to retest, based on your specific index profile.

The indexes are most useful when treated as a starting point for a structured intervention, not a one-time snapshot. If your Glycan Mature Index is elevated, the next step is a conversation with your clinician about hormonal health. If your Glycan Shield is low, nutritional status is worth investigating. If your Glycan Bisection index is high, it may reflect how stress and lifestyle factors are aging your immune system, making sleep quality and stress load the primary levers to examine.

If you are ready to see what your own glycan indexes reveal, order your GlycanAge test kit and book your personal interpretation call to walk through your full five-index report with a specialist.

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External sources

• https://pmc.ncbi.nlm.nih.gov/articles/PMC4049143/ — Kristić J, Vučković F, Menni C, et al. Glycans are a novel biomarker of chronological and biological ages. J Gerontol A Biol Sci Med Sci. 2014;69(7):779-789.

• https://pubmed.ncbi.nlm.nih.gov/29572115/ — Gudelj I, Salo PP, Trbojević-Akmačić I, Albers M, Primorac D, Perola M, Lauc G. Low galactosylation of IgG associates with higher risk for future diagnosis of rheumatoid arthritis during 10 years of follow-up. Biochim Biophys Acta Mol Basis Dis. 2018;1864(6 Pt A):2034-2039.

• https://www.ncbi.nlm.nih.gov/books/NBK513460/ — Patel P, Jamal Z, Ramphul K. Immunoglobulin. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023.

• https://www.cms.gov/medicare/quality/clinical-laboratory-improvement-amendments — CMS: Clinical Laboratory Improvement Amendments (CLIA)