HealthWise KnowledgeBase
Blood Glucose
Results
Normal
A blood glucose test measures the amount of a type of sugar, called glucose, in your blood.
Results are often ready in 1 to 2 hours. Glucose levels in a blood sample taken from your vein (called a blood plasma value) may differ a little than glucose levels checked with a finger stick.
The normal values listed here—called a reference range—are just a guide. These ranges vary from lab to lab, and your lab may have a different range for what's normal. Your lab report should contain the range your lab uses. Also, your doctor will evaluate your results based on your health and other factors. This means that a value that falls outside the normal values listed here may still be normal for you or your lab.
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Fasting blood glucose:Reference 1 |
Less than or equal to 100 milligrams per deciliter (Reference mg/dL Opens New Window) (5.6 millimoles per liter, or Reference mmol/L Opens New Window). |
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2 hours after eating (Reference postprandial Opens New Window):Reference 2 |
Less than 140 mg/dL (7.8 mmol/L) for people age 50 and younger; less than 150 mg/dL (8.3 mmol/L) for people ages 50–60; less than 160 mg/dL (8.9 mmol/L) for people age 60 and older. |
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Random (casual):Reference 3 |
Levels vary depending on when and how much you ate at your last meal. In general: 80–120 mg/dL (4.4–6.6 mmol/L) before meals or when waking up; 100–140 mg/dL (5.5–7.7 mmol/L) at bedtime. |
Many conditions can change your blood glucose levels. Your doctor will discuss any significant abnormal results with you in relation to your symptoms and past health.
For more information on results from an oral glucose tolerance test or glycohemoglobin A1c test, see:
High values
You may have diabetes. To make a diagnosis of type 2 diabetes, your doctor will use the Reference American Diabetes Association's criteria.
Other conditions that can cause high blood glucose levels include:
- Severe stress.
- Reference Heart attack Opens New Window.
- Reference Stroke Opens New Window.
- Reference Cushing's syndrome Opens New Window.
- Medicines such as Reference corticosteroids Opens New Window.
- Excess production of growth hormone (Reference acromegaly Opens New Window).
Low values
A fasting glucose level below 40 mg/dL (2.2 mmol/L) in women or below 50 mg/dL (2.8 mmol/L) in men that is accompanied by symptoms of Reference hypoglycemia Opens New Window may mean you have an insulinoma, a tumor that produces abnormally high amounts of insulin.
Low glucose levels also may be caused by:
- Reference Addison's disease Opens New Window.
- Decreased thyroid hormone levels (Reference hypothyroidism Opens New Window).
- A tumor in the Reference pituitary gland Opens New Window.
- Liver disease, such as Reference cirrhosis Opens New Window.
- Kidney failure.
- Malnutrition or an eating disorder, such as Reference anorexia Opens New Window.
- Medicines used to treat diabetes.
| By: | Reference Healthwise Staff | Last Revised: Reference August 15, 2012 |
| Medical Review: | Reference E. Gregory Thompson, MD - Internal Medicine
Reference Alan C. Dalkin, MD - Endocrinology |
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This information does not replace the advice of a doctor. Healthwise, Incorporated disclaims any warranty or liability for your use of this information. Your use of this information means that you agree to the Reference Terms of Use. Reference How this information was developed to help you make better health decisions.
