Normal Fasting Blood Sugar Levels Chart:
What Your Morning Glucose Means

Written by: Dr. Albana Greca Sejdini, MD, MMedSc  •  Medically reviewed by: Dr. Ruden Cakoni, MD, Endocrinologist  •  Updated: August 2026

Quick Answer

For most nonpregnant adults who do not already have diabetes, a laboratory fasting plasma glucose below 100 mg/dL (5.6 mmol/L) is considered normal for diagnostic purposes. A result of 100–125 mg/dL (5.6–6.9 mmol/L) is in the prediabetes range, while 126 mg/dL (7.0 mmol/L) or higher meets the laboratory threshold for diabetes when confirmed as recommended.

A fasting test means no calories for at least 8 hours; plain water is generally allowed. A home glucose meter is useful for following patterns, but it should not be used by itself to diagnose diabetes.

When my patients show me a morning glucose result, I usually ask two questions first: Was this a true fasting reading? and is this one isolated number or a repeated pattern? Sleep, stress, illness, late meals, medications, hormonal changes and normal biological variation can all influence a single morning reading.

Normal Fasting Blood Sugar Levels Chart

Fasting glucose mmol/L What it may mean What to do
Below 70 mg/dL Below 3.9 Low-glucose alert level, especially with insulin or medicines that can cause hypoglycemia Follow your low-glucose plan and discuss repeated lows with your healthcare professional
70–99 mg/dL 3.9–5.5 Usually within the normal fasting range Continue routine health checks and healthy habits
100–125 mg/dL 5.6–6.9 Prediabetes range on laboratory fasting plasma glucose Discuss repeat testing, HbA1c and your overall diabetes risk
126 mg/dL or higher 7.0 or higher Diabetes diagnostic range when confirmed appropriately Arrange medical evaluation and laboratory confirmation
Important: These diagnostic ranges apply to laboratory fasting plasma glucose. Pregnancy follows different testing pathways and glucose cutoffs. Home glucose meters and continuous glucose monitors are valuable for monitoring but are not substitutes for appropriate diagnostic laboratory testing.

If your result is close to a cutoff, your doctor may recommend an HbA1c test, another fasting plasma glucose test, or an oral glucose tolerance test. These tests measure glucose differently, so they do not always identify exactly the same people.

If You Already Have Diabetes, Your Target Is Different

This is an important distinction. The 100–125 mg/dL prediabetes and 126 mg/dL diabetes numbers above are used for diagnosis. They are not the same as treatment targets for someone who already has diabetes.

For many nonpregnant adults living with diabetes, an individualized premeal glucose target of about 80–130 mg/dL (4.4–7.2 mmol/L) may be appropriate. Your personal target may be different depending on age, medications, risk of hypoglycemia, pregnancy, other health conditions and your overall treatment plan.

So, for example, a fasting glucose of 120 mg/dL can fall in the prediabetes diagnostic range for a person who has not been diagnosed, while that same glucose level may be within the treatment target of some people who already have diabetes. It does not mean that their diabetes has changed back into prediabetes.

What Does Fasting Blood Sugar Mean?

Fasting blood sugar is the amount of glucose in your blood after you have had no food or caloric drinks for at least 8 hours. It is usually measured in the morning before breakfast.

Even while you sleep, your body needs glucose. The liver releases glucose into the bloodstream to supply the brain and other organs. Insulin helps keep this glucose within an appropriate range. When insulin resistance develops, or when the pancreas cannot provide enough effective insulin, fasting glucose can rise.

Fasting glucose is only one part of diabetes evaluation. Your doctor may combine it with other blood tests for diabetes, symptoms, family history, medications, weight and waist changes, pregnancy status and other medical information.

Why Is My Fasting Blood Sugar High in the Morning?

This is one of the questions I hear most often from patients. You may go to bed with a reasonable glucose level and wake with a higher result even though you did not eat overnight.

During the early morning hours, hormones such as cortisol and growth hormone help prepare your body to wake. They may stimulate the liver to release glucose. In people with insulin resistance or diabetes, the body may not remove that extra glucose from the bloodstream as efficiently. This is commonly called the dawn phenomenon.

Possible reason How it may affect morning glucose
Dawn phenomenon Early-morning hormones can increase liver glucose release.
Late dinner or evening snacks A large or carbohydrate-heavy meal may keep glucose elevated overnight.
Poor sleep or stress Stress hormones can increase glucose production and insulin resistance.
Illness, pain or inflammation The body's stress response may temporarily raise glucose.
Medication timing Treatment may need review, but medicines should not be adjusted without professional advice.
Insulin resistance The body may require more insulin to control glucose released overnight.

If your morning readings are repeatedly high, record them together with your evening meal, sleep, stress, activity, illness and medications. You may also find it helpful to read about stress and blood sugar and how insulin resistance is evaluated.

high fasting sugar causes

What Should You Do If Your Fasting Blood Sugar Is High?

  1. Check whether it was a true fast. Aim for at least 8 hours without calories.
  2. Confirm an unexpected home reading. Wash and dry your hands and repeat the test with a fresh strip when appropriate.
  3. Look for a pattern. Several readings are more informative than one isolated result.
  4. Review the previous evening. Consider meals, alcohol, poor sleep, stress, illness, pain and unusual activity.
  5. Ask whether laboratory testing is appropriate. Your healthcare professional may suggest fasting plasma glucose, HbA1c or another test.
  6. Do not change insulin or diabetes medication on your own. Dose and timing changes must be individualized.
practical steps for high fasting sugar

Is a Fasting Blood Sugar of 100 mg/dL Normal?

A laboratory fasting plasma glucose of 100 mg/dL (5.6 mmol/L) is at the lower boundary of the prediabetes range. It does not mean that you have diabetes.

If I see a borderline result in a patient, I look at whether it repeats and consider HbA1c, family history, weight and waist trend, blood pressure, activity, sleep and medications. A borderline result deserves follow-up, but it is not an emergency.

Does a Fasting Blood Sugar of 126 mg/dL Mean Diabetes?

A laboratory fasting plasma glucose of 126 mg/dL (7.0 mmol/L) or higher meets the diagnostic threshold for diabetes. In a person without unequivocal hyperglycemia or a hyperglycemic crisis, the diagnosis generally needs confirmation with another abnormal result.

A single home-meter reading of 126 mg/dL does not diagnose diabetes. If you repeatedly see fasting readings around or above this level, arrange appropriate laboratory testing with your healthcare professional.

When Is Fasting Blood Sugar Too Low?

A glucose reading below 70 mg/dL (3.9 mmol/L) is an important low-glucose alert level, particularly for people taking insulin or medicines that can cause hypoglycemia. Symptoms may include shaking, sweating, hunger, dizziness, weakness, palpitations, blurred vision or confusion.

If you have diabetes, follow the hypoglycemia plan given to you by your healthcare professional. Severe symptoms, seizure, loss of consciousness or inability to swallow safely require urgent help.

Fasting Blood Sugar vs. HbA1c

Test What it shows Fasting?
Fasting plasma glucose Glucose at one point in time after an overnight fast Yes
HbA1c Average glucose exposure over approximately the previous 2–3 months No

These tests can sometimes disagree. Someone may have fasting glucose below the prediabetes threshold while HbA1c is elevated, or the reverse. This is why I prefer to interpret laboratory results together rather than relying on a single number.

Doctor's Note

When I talk with my patients about fasting glucose, I remind them that a number is information, not a judgment. One morning result can be affected by temporary factors. Repeated results, however, may reveal an important trend. If your fasting glucose is gradually rising, acting early with appropriate nutrition, movement, sleep, weight management and medical care can make a meaningful difference.

When Should You Contact a Doctor?

Arrange routine medical follow-up if you do not already have diabetes and laboratory or home fasting readings repeatedly fall around 100–125 mg/dL. Your doctor may recommend formal screening or repeat testing.

Arrange laboratory evaluation if fasting home readings repeatedly reach 126 mg/dL or higher, or if a laboratory fasting glucose is in the diabetes range.

Also contact your healthcare professional if glucose is repeatedly below 70 mg/dL, especially if you use insulin or medication that can cause hypoglycemia, or if you develop persistent excessive thirst, frequent urination, unexplained weight loss, blurred vision or marked fatigue.

Seek urgent medical care for severe or worsening symptoms such as repeated vomiting, severe dehydration, confusion, difficulty breathing, inability to keep fluids down, seizure, loss of consciousness or other signs of a glucose emergency.

Most Asked Questions

What is a normal fasting blood sugar?

For diagnostic purposes, normal laboratory fasting plasma glucose is below 100 mg/dL (5.6 mmol/L). The usual 70–99 mg/dL range is commonly shown because readings below 70 mg/dL are considered a low-glucose alert level.

Is fasting blood sugar of 110 mg/dL high?

A laboratory fasting glucose of 110 mg/dL (6.1 mmol/L) falls in the prediabetes range for someone who has not already been diagnosed with diabetes. One result alone should be interpreted in context.

Can I drink water before a fasting glucose test?

Plain water is generally allowed. Fasting means avoiding food and caloric drinks for at least 8 hours. Follow any specific instructions given by your laboratory or healthcare professional.

Does normal fasting glucose change with age?

The diagnostic fasting-glucose thresholds are not simply raised because an adult is older. However, treatment targets for people who already have diabetes may be individualized according to age, overall health, hypoglycemia risk, other illnesses and functional status.

Can stress raise fasting blood sugar?

Yes. Stress hormones such as cortisol and adrenaline can increase glucose release from the liver. Stress may also affect sleep, eating, activity and medication routines.

Can fasting glucose be normal while HbA1c is high?

Yes. Fasting glucose is one measurement, while HbA1c reflects longer-term glucose exposure. Some people develop higher after-meal glucose even when their fasting result remains below the diagnostic cutoff.

Can a home glucose meter diagnose diabetes?

No. Home meters are useful for monitoring glucose patterns, but diagnosis should be made using appropriate clinical and laboratory testing.

Related Questions

Related Resources

Educational Safety Note

This page is for education and does not provide an individual diagnosis or treatment plan. Diagnostic glucose thresholds are based on appropriate laboratory testing and must be interpreted in clinical context. Do not start, stop or change insulin or diabetes medication because of information on this page without guidance from your healthcare professional.

References

  1. American Diabetes Association Professional Practice Committee. Diagnosis and Classification of Diabetes: Standards of Care in Diabetes—2026.
  2. American Diabetes Association Professional Practice Committee. Glycemic Goals, Hypoglycemia, and Hyperglycemic Crises: Standards of Care in Diabetes—2026.
  3. National Institute of Diabetes and Digestive and Kidney Diseases. Diabetes Tests & Diagnosis.