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Glucose, Serum or Plasma (Mass Concentration)

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

This test measures the amount of glucose (sugar) in your blood, typically drawn from serum or plasma. It helps monitor blood sugar levels for conditions like diabetes.

Quick summary

["Glucose levels indicate how your body uses energy and can signal diabetes or other metabolic issues."]

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

Key facts at a glance

LOINC
48989-8
Short code
Glucose 6 PM SerPl-mCnc
Synonyms
Glucose 6 PM SerPl-mCnc
Category
glucose
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Ref low
70
Ref high
100
Critical range
50 N/A – 400 N/A
Fasting
true
Population
adult
Sex
all
Age range
18–65 years
CPT
82947
SNOMED
260395008
Specimen volume
5 mL
Stability
Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
Hemolysis max
500
Lipemia max
1000
Icterus max
500
TAT
4–24 hours
Order
routine

Why It’s Done

Your healthcare provider may order this test to check for diabetes, monitor blood sugar control, diagnose hypoglycemia (low blood sugar), or assess how your body processes glucose, especially if you have symptoms like excessive thirst, fatigue, or frequent urination.

What to Expect Before the Test

No special preparation is usually needed, but you may be asked to fast (not eat) for 8–12 hours before the test if it’s part of a fasting glucose panel. If you’re unsure, ask your provider. The blood is drawn from a vein in your arm.

What Happens During the Test

A small needle is inserted into your arm to collect blood, which is then sent to a lab for analysis. The process takes a few minutes, and you may feel a brief pinch. The sample is tested for glucose concentration using a standardized method.

What the Results Mean

Results are compared to general reference ranges, but your individual results will be interpreted by your healthcare provider based on your medical history and symptoms. High or low glucose levels may trigger further testing or adjustments to treatment.

Reference range

Fasting: 70-100 mg/dLN/A

Specimen: serum

Fasting for 8-12 hours required. Water is permitted. Avoid chewing gum and smoking before the test.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Glucose levels are critical for diagnosing diabetes (e.g., fasting glucose ≥126 mg/dL or random glucose ≥200 mg/dL with symptoms) or detecting prediabetes. Chronic high glucose can damage blood vessels and nerves over time. Low glucose may require immediate medical attention, especially if you feel dizzy or shaky.

Short name

Glucose Level

Frequently asked questions

What causes abnormal glucose levels?
Abnormal glucose results can stem from conditions like diabetes, hormonal imbalances (e.g., thyroid issues), infections, stress, or medications (e.g., steroids). Lifestyle factors like diet, exercise, or obesity may also play a role. Always discuss symptoms or concerns with your provider.
How often should I get this test?
Frequency depends on your health status. People with diabetes typically check glucose levels monthly or more often as directed by their doctor. Routine screenings for prediabetes or diabetes may occur every 1–3 years, but your provider will tailor recommendations to your needs.
Can diet or exercise affect test results?
Yes. Fasting before the test ensures accurate fasting glucose readings. Eating or drinking (except water) can raise glucose levels. Exercise may temporarily lower glucose, so timing your test around your activity schedule is important. Ask your provider for guidance tailored to your routine.
  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