Blood Gluclose Reading

Glucose, the body’s main energy source, comes primarily from carbohydrates in food and drinks. Your blood carries glucose to all cells for energy, with various processes regulating blood glucose levels. Insulin, a hormone produced by the pancreas, plays a key role in maintaining these levels. High blood glucose (hyperglycemia) often indicates diabetes, a condition where the pancreas produces insufficient insulin, or the body doesn’t respond to it effectively.

What is a blood glucose (sugar) test?

A blood glucose test measures the level of glucose (sugar) in your blood, primarily to screen for diabetes. There are two main types:

• Capillary Blood Glucose Test: A drop of blood, usually from a fingertip prick, is tested using a glucose meter (glucometer) for quick results.
• Venous (Plasma) Blood Glucose Test: A sample is taken from a vein and analyzed in a lab, typically as part of a larger blood panel. This method is more accurate than the capillary test.

Fasting blood glucose tests are often used to provide a clearer picture of your baseline sugar levels. For individuals with diabetes, especially Type 1, regular monitoring through at-home testing or continuous glucose monitoring (CGM) devices is essential for managing blood sugar levels effectively.

When would I need a blood glucose test?

There are three primary reasons for needing a blood glucose test:

• Your healthcare provider may include it as part of routine bloodwork, such as a basic metabolic panel (BMP) or a comprehensive metabolic panel (CMP).
• You may be experiencing symptoms of high or low blood sugar, possibly indicating diabetes or another condition.
• If you take long-term medications that affect blood sugar, such as corticosteroids, regular glucose tests may be required to monitor your levels.

Blood glucose tests are commonly used to screen for Type 2 diabetes (T2D), a prevalent condition, especially for those with risk factors. The American Diabetes Association recommends regular screening for individuals 35 and older. Providers may also order a test if you exhibit symptoms of high blood sugar (hyperglycemia) or low blood sugar (hypoglycemia).

Symptoms of high blood sugar include:

• Excessive thirst (polydipsia)
• Frequent urination (polyuria)
• Fatigue
• Intense hunger (polyphagia)
• Unexplained weight loss
• Blurred vision
• Slow healing of cuts or sores. 

What is the normal glucose level in a blood test?

A normal fasting blood glucose level for someone without diabetes typically ranges from 70 to 99 mg/dL (3.9 to 5.5 mmol/L). In some cases, values between 50 and 70 mg/dL (2.8 to 3.9 mmol/L) may also be considered normal for individuals without diabetes.

What does a high blood glucose level mean?

If your fasting blood glucose level is between 100 and 125 mg/dL (5.6 to 6.9 mmol/L), it indicates prediabetes. Individuals with prediabetes have a 50% chance of developing Type 2 diabetes within 5 to 10 years, but preventive measures can be taken to reduce this risk. A fasting blood glucose level of 126 mg/dL (7.0 mmol/L) or higher on more than one occasion is typically associated with diabetes.

In either instinct, your healthcare provider may request an A1c test, which measures your blood sugar levels over the past few months, to confirm a diagnosis of prediabetes or diabetes.

The most common types of diabetes include:

• Type 2 diabetes (T2D): Occurs when the pancreas does not produce enough insulin or the body becomes resistant to insulin, causing high blood sugar levels.
• Type 1 diabetes (T1D): An autoimmune condition where the immune system attacks insulin-producing cells in the pancreas, leading to very high blood glucose levels.
• Gestational diabetes: A form of diabetes that develops during pregnancy, typically between 24 and 28 weeks, and usually resolves after childbirth.

Other causes of high glucose levels

• Adrenal gland disorders, such as Cushing syndrome.
• Pancreatic conditions, like pancreatitis.
• Hyperthyroidism.
• High levels of stress, such as from surgery or trauma.
• Certain medications, particularly corticosteroids.

What does a low blood glucose level mean?

A blood sugar level of 70 mg/dL or lower is generally considered low. Hypoglycemia, or low blood sugar, is common in individuals with Type 1 diabetes and in those with Type 2 diabetes who take specific medications. However, it is much rarer in people without diabetes.

For those without diabetes, low blood glucose levels may indicate conditions such as:

• Liver disease
• Kidney disease
• Hypothyroidism
• Addison’s disease (adrenal insufficiency)
• Alcohol use disorder (AUD)
• Insulinoma (a rare tumor)

These conditions typically cause recurring episodes of low blood sugar. A single low blood sugar reading in someone without diabetes is usually not a cause for concern.

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References:

American Diabetes Association. (2023). Standards of medical care in diabetes—2023. Retrieved from https://www.diabetes.org

Professional, C. C. Medical. (2024, June 14). Blood glucose (sugar) test: Levels & What They mean. Cleveland Clinic. https://my.clevelandclinic.org/health/diagnostics/12363-blood-glucose-test#overview