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Fructosamine

Fructosamine measures sugar-coated proteins in your blood, mostly albumin, and reflects your average blood sugar over the last 2 to 4 weeks.

AI-verified against cited sources. Awaiting expert reviewAlso called FRA, GSPLOINC 15069-8

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What it is

When there is extra sugar in the blood, some of it attaches to blood proteins. Fructosamine is the total of these sugar-coated proteins, and most of it is albumin. Because albumin turns over in a few weeks, the result reflects average blood sugar over roughly the last 2 to 4 weeks, a shorter window than A1c. Some labs report this as glycated serum protein.

Why it matters

Fructosamine is used mainly by people with diabetes, when A1c may not be reliable (for example with some hemoglobin variants, anemia or kidney failure) or when a clinician wants to see the effect of a treatment change sooner. The ADA says it can be used for monitoring when an alternative to A1c is needed, but the evidence for it is much weaker than for A1c.

If it’s low

A low fructosamine means average blood sugar has been lower over the last few weeks, which is usually fine. Conditions that change blood proteins can also shift the number, so a low result that does not match your glucose readings is worth discussing.

Common causes

  • Blood sugar that has been in a healthy range
  • Conditions that change blood proteins, such as nephrotic syndrome or liver cirrhosis, which can move the result

What can help

  • Ask your clinician whether albumin or total protein should be checked alongside it

If it’s high

A high fructosamine means blood sugar has been higher on average over roughly the past 2 to 4 weeks. In someone with diabetes it suggests glucose control has slipped recently, and it is best read alongside glucose readings or A1c. Changes in blood protein can also move the number.

Common causes

  • Diabetes with higher average blood sugar
  • Changes in diabetes medicines, food or activity
  • Illness or other stress that raised blood sugar

What can help

  • Ask your clinician how this compares with your glucose readings and A1c
  • Ask whether recent treatment changes could show up in this result

Usual ranges

What labs print as the reference range, by who was tested. Ranges differ a little between labs, so the range on your own report is the one your result is judged against.

For adults: 205–285 µmol/L. Source: Quest Diagnostics, Labcorp, Practical Laboratory Medicine.

What can affect your result

  • Albumin and total protein levels
  • Kidney disease with protein loss, liver cirrhosis and thyroid disease
  • Pregnancy, which has its own ranges
  • Immunoglobulin levels
  • The assay and lab, since reference intervals differ
  • Conditions that change blood protein or albumin levels, such as nephrotic syndrome, liver cirrhosis and thyroid disease, can make fructosamine misleading.
  • High immunoglobulin levels (for example IgA in celiac disease) can influence the result.
  • High-dose vitamin C can interfere with some methods, so ask your lab whether to pause supplements before the test.
  • Pregnancy: fructosamine changes with gestational age, so non-pregnant ranges do not apply.

About 2 to 4 weeks of average blood sugar, shorter than A1c.

When to talk to a clinician

Talk with your clinician soon if your fructosamine is high and you have heavy thirst, frequent urination, blurred vision or unplanned weight loss. Get urgent help for vomiting, belly pain, trouble breathing or confusion together with high blood sugar.

Questions you could ask

  • Why is fructosamine useful for me instead of, or alongside, A1c, and how often should we repeat it?
  • How does this compare with my glucose readings or A1c?
  • Could my albumin or protein levels be affecting the result?
  • Could a condition that affects my blood proteins be changing this result?

Questions people ask

Why would my clinician order fructosamine instead of A1c?

A1c depends on red blood cells. If those are unusual (for example from a hemoglobin variant, anemia or kidney failure), A1c can be misleading. Fructosamine depends on blood proteins instead, and it shows changes sooner, over about 2 to 4 weeks.

Is fructosamine the same as glycated albumin?

They are related but not identical. Fructosamine measures sugar on all serum proteins, mostly albumin. Glycated albumin measures the share of albumin that is sugar-coated, which adjusts for your albumin level. The two track each other closely.

Is there a standard A1c equivalent for fructosamine?

No. Researchers have published equations, but they vary with the test method and the people studied, so it is best not to convert the number yourself. Ask your clinician how to compare the two.

Show the science and sources

Is a change real?

Fructosamine naturally varies about 3.4% from test to test in the same healthy person. Between two results from the same lab, a change of roughly 11% or more is unlikely to be day-to-day noise or lab variation (95% reference change value). Source: Desirable Biological Variation Database specifications, 2014 update (Minchinela J, Ricos C, et al.; the 'Ricos database', a compilation of median published CVI/CVG).

For clinicians and researchers

Fructosamine is the sum of ketoamines formed by non-enzymatic glycation of serum proteins, predominantly albumin (about 60 to 70% of serum protein, half-life about 20 days), so it reflects glycemia over about 2 to 4 weeks (ADA 2026) or 15 to 30 days (NACB/ADA 2011), compared with 60 to 120 days for A1c. The classic assay is the nitroblue tetrazolium colorimetric method. Fructosamine and glycated albumin correlate closely (r = 0.86 in one comparison), but glycated albumin is expressed as a share of total albumin and so adjusts for albumin concentration. Levels can be altered in protein-losing states such as nephrotic syndrome, in reduced protein production such as cirrhosis, and in thyroid disease, and they vary with gestational age in pregnancy (Danese 2015). ADA 2026 Section 6 recommends fructosamine or CGM for glycemic monitoring when an alternative to A1c is required (grade B), notes the evidence base is much weaker than for A1c, and Section 2 advises considering fructosamine or glycated albumin when glucose and A1c are persistently discordant. The NACB/ADA 2011 guideline says the clinical utility of glycated proteins other than hemoglobin has not been clearly established. Reference intervals are assay and population specific: Quest and Labcorp both print 205 to 285 µmol/L (Labcorp for ages 20 to 60), and published intervals include 202 to 296 (New Zealand), 195 to 258 (US adults without diabetes), 215 to 287 for ages 20 to 65 and 226 to 325 above 65 (China), and 186 to 248 for women and 196 to 269 for men (Brazil). There is no standard conversion to A1c, because published equations depend on the assay and the group studied.

LOINC 15069-8 (primary), 33805-3. Specimen: serum-or-plasma.

Sources

  1. Fructosamine (test code 8340), Quest Diagnostics
  2. Fructosamine (test 100800), Labcorp
  3. Establishing a blood fructosamine reference range for the Brazilian population based on data from ELSA-Brasil, Practical Laboratory Medicine (2019)
  4. Fructosamine Testing for Glycemic Control: When and Why to Order Fructosamine Tests and How to Interpret the Results, ADCES Connect (Association of Diabetes Care & Education Specialists) (2024)
  5. 6. Glycemic Goals, Hypoglycemia, and Hyperglycemic Crises: Standards of Care in Diabetes-2026, American Diabetes Association (Diabetes Care) (2026)
  6. 2. Diagnosis and Classification of Diabetes: Standards of Care in Diabetes-2026, American Diabetes Association (Diabetes Care) (2026)
  7. Advantages and Pitfalls of Fructosamine and Glycated Albumin in the Diagnosis and Treatment of Diabetes, Journal of Diabetes Science and Technology (2015)
  8. Guidelines and recommendations for laboratory analysis in the diagnosis and management of diabetes mellitus, Diabetes Care (NACB and ADA) (2011)

AI-verified against cited sources. Awaiting expert review. Last reviewed 2026-10-03. How we build and check these pages.

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