Blood Sugar Levels Chart: Normal Ranges by Age, Fasting & After Eating

What is a normal blood sugar level? Is 90 mg/dL healthy? What about 100, 110, or 120?

The answer depends on when your blood sugar is measured, which test is used, and whether you have diabetes.

For adults without diabetes, a fasting laboratory blood glucose level below 100 mg/dL is considered normal. A result of 100–125 mg/dL falls within the prediabetes range, while 126 mg/dL or higher meets a diabetes diagnostic threshold when appropriately confirmed.

But fasting results are only one part of the picture. Blood sugar changes throughout the day, and A1C, post-meal readings, and diabetes management targets serve different purposes.

This guide brings the key reference ranges together in clear charts, based on the American Diabetes Association (ADA) Standards of Care in Diabetes—2026.

Normal Blood Sugar Levels Chart

The chart below compares the main laboratory criteria used to classify normal glucose levels, prediabetes, and diabetes in nonpregnant individuals.

Test	Normal	Prediabetes	Diabetes
Fasting plasma glucose	Below 100 mg/dL	100–125 mg/dL	126 mg/dL or higher
A1C	Below 5.7%	5.7–6.4%	6.5% or higher
2-hour 75g OGTT	Below 140 mg/dL	140–199 mg/dL	200 mg/dL or higher

Source: ADA Standards of Care in Diabetes—2026, Section 2.

Important: These are laboratory diagnostic criteria, not universal targets for daily home glucose readings.

An oral glucose tolerance test (OGTT) measures the body's response to a standardized glucose drink. Its two-hour thresholds should not be applied directly to an ordinary meal.

Likewise, diabetes is generally not diagnosed from a single home glucose reading. In the absence of unequivocal hyperglycemia, confirmatory laboratory testing is required.

Blood Sugar Targets for Adults With Diabetes

People already diagnosed with diabetes generally use different numbers to guide day-to-day management.

Measurement	ADA General Target
Before meals	80–130 mg/dL
Peak after meals	Below 180 mg/dL
A1C	Below 7%

These targets apply to many nonpregnant adults with diabetes. Individual goals may be higher or lower depending on treatment, age, health status, and risk of hypoglycemia.

The difference matters: a fasting glucose of 115 mg/dL may fall within the laboratory prediabetes range for someone being screened, while a pre-meal reading of 115 mg/dL may be within the management target for someone with diagnosed diabetes.

What Is a Normal Blood Sugar Range for Adults?

Blood glucose is not fixed at one number. It naturally changes with eating, physical activity, sleep, medication, and hormonal responses.

For adults without diabetes, the clearest established reference values come from laboratory tests performed under defined conditions.

Fasting plasma glucose below 100 mg/dL and A1C below 5.7% are considered normal by ADA diagnostic criteria.

A random glucose reading, however, is more difficult to interpret without knowing when you last ate. There is no single random-glucose cutoff that separates normal glucose from prediabetes.

For someone with classic symptoms of high blood sugar, a laboratory random plasma glucose result of 200 mg/dL or higher can meet a diabetes diagnostic criterion.

If you are uncertain about a reading, consider the testing circumstances before comparing it with a chart.

Blood Sugar Levels by Age

Many online charts suggest that people in their 20s, 40s, or 60s should have completely different normal blood sugar ranges.

That interpretation is misleading.

The standard laboratory diagnostic thresholds for diabetes and prediabetes do not automatically increase with age for nonpregnant adults.

However, blood sugar management targets may change with age, particularly for older adults living with diabetes.

Blood Sugar by Age: What Actually Changes?

Age Group	How to Interpret Blood Sugar
Adults 18–39	Standard adult laboratory diagnostic thresholds generally apply.
Adults 40–64	The same diagnostic thresholds apply; screening needs depend on individual risk.
Adults 65 and older	Diagnostic thresholds remain applicable, but diabetes management goals may be individualized more extensively.

Age alone does not make a fasting laboratory result of 120 mg/dL normal.

Blood Sugar Targets for Older Adults With Diabetes

The ADA 2026 guidelines recommend considering overall health, functional ability, other medical conditions, and hypoglycemia risk when establishing targets.

For example:

Older Adult Health Status	Example A1C Goal
Generally healthy, with stable health conditions	Below 7.0–7.5%
More complex health needs or functional limitations	Often below 8.0%, when appropriate
Very complex or poor health	Prioritize avoiding hypoglycemia and symptomatic hyperglycemia rather than relying on a strict A1C target

These are examples of clinical management goals, not age-based definitions of normal blood sugar.

Children, pregnant individuals, and people with gestational diabetes require separate guidance.

Fasting Blood Sugar Levels Chart

Fasting blood sugar is one of the most commonly used measurements for diabetes screening.

A fasting plasma glucose test generally requires no caloric intake for at least eight hours before the blood sample is collected.

What Do Different Fasting Blood Sugar Numbers Mean?

Fasting Glucose	Interpretation
70–89 mg/dL	Below the prediabetes threshold
90–99 mg/dL	Within the normal laboratory range
100–109 mg/dL	Within the prediabetes range
110–125 mg/dL	Within the prediabetes range
126 mg/dL or higher	Meets a diabetes diagnostic threshold when confirmed

This chart assumes laboratory fasting plasma glucose testing. The 70–89 category is illustrative and does not establish a universal lower limit of normal.

Is a Fasting Blood Sugar of 100 or 110 Normal?

Under ADA laboratory criteria, fasting glucose of 100–125 mg/dL falls within the prediabetes range.

However, a single result does not necessarily mean you will develop diabetes.

Stress, illness, medications, and testing conditions can influence glucose results. Your healthcare professional may recommend repeat testing or A1C to understand the broader pattern.

If you have diabetes, do not use this diagnostic chart as your personal treatment target. Your prescribed glucose goals may differ.

Blood Sugar Levels After Eating

Blood sugar normally rises after eating as carbohydrates are digested and glucose enters the bloodstream.

For people without diabetes, a two-hour glucose value below 140 mg/dL is often used as a broad reference. However, that established cutoff comes from a standardized 75g OGTT, not an everyday meal.

For many nonpregnant adults with diabetes, the ADA recommends a peak post-meal target below 180 mg/dL, generally checked one to two hours after the beginning of a meal.

There is no universally established one-hour diagnostic cutoff after an ordinary meal.

A reading of 140, 160, or 180 mg/dL should therefore be interpreted in context rather than judged by one number alone.

For a detailed explanation of meal timing, glucose fluctuations, and specific post-meal readings, see our guide: Blood Sugar After Eating: What's Normal and When to Pay Attention.

A1C Chart: How It Compares With Blood Sugar

A1C measures the percentage of hemoglobin with glucose attached and provides an estimate of average blood glucose exposure over approximately two to three months.

Unlike a finger-prick reading, it does not measure your glucose at one particular moment.

A1C to Estimated Average Glucose (eAG) Chart

A1C	Estimated Average Glucose
5.0%	97 mg/dL
5.5%	111 mg/dL
6.0%	126 mg/dL
6.5%	140 mg/dL
7.0%	154 mg/dL
8.0%	183 mg/dL
9.0%	212 mg/dL

Source: American Diabetes Association A1C-to-eAG conversion formula. Values are approximate population-based estimates.

A1C and estimated average glucose are related, but they are not identical to fasting glucose.

For example, an A1C of 6% corresponds to an estimated average glucose of approximately 126 mg/dL. It does not mean your fasting blood sugar is always 126 mg/dL.

A1C can also be less reliable in certain medical circumstances, including conditions affecting red blood cell turnover and some hemoglobin variants.

Your healthcare professional can help determine whether A1C accurately reflects your glucose status.

When Is Blood Sugar Too High or Too Low?

Blood sugar readings are meaningful only when interpreted alongside symptoms, timing, medical history, and treatment.

Low Blood Sugar

Blood glucose below 70 mg/dL is considered low, particularly in diabetes management.

Symptoms can include shakiness, sweating, hunger, dizziness, or confusion.

For an alert person who can safely swallow, the CDC recommends the 15-15 rule for treating low blood sugar: consume 15 grams of fast-acting carbohydrate, wait 15 minutes, and recheck glucose. Repeat if it remains below 70 mg/dL.

Very low glucose, especially below 55 mg/dL, or symptoms such as seizures or loss of consciousness require immediate assistance. Severe hypoglycemia may require glucagon and emergency medical care. Never give food or drink to someone who cannot safely swallow.

High Blood Sugar

A fasting laboratory glucose result of 126 mg/dL or higher or an A1C of 6.5% or higher meets a diabetes diagnostic threshold when properly confirmed.

Repeated elevated readings, increased thirst, frequent urination, unexplained weight loss, or unusual fatigue should prompt medical evaluation.

If high glucose is accompanied by vomiting, abdominal pain, rapid or deep breathing, or confusion, seek urgent medical care.

How to Read Your Blood Sugar Results

Before deciding what a glucose number means, ask three questions.

1. Was the test fasting, after a meal, or random?

A fasting laboratory result cannot be interpreted using the same criteria as a post-lunch glucose reading.

2. Was it measured by a laboratory, finger-prick meter, or CGM?

Laboratory plasma tests are used for formal diagnosis. Home glucose meters and CGMs provide information for monitoring but are not interchangeable with diagnostic laboratory measurements.

CGMs measure glucose in interstitial fluid and may lag behind blood glucose during rapid changes.

3. Is this one reading or a repeated pattern?

A single unexpected value is less informative than results considered over time and alongside symptoms.

For people without diabetes, routine home glucose monitoring is not automatically necessary. Appropriate testing should be guided by individual risk and medical advice.

Frequently Asked Questions

What Is a Good Blood Sugar Level in the Morning?

For adults without diabetes, fasting laboratory glucose below 100 mg/dL is considered normal. Morning results should be interpreted based on whether you actually fasted and whether you have diabetes.

Is 90 mg/dL a Normal Blood Sugar Level?

Yes. A fasting plasma glucose result of 90 mg/dL is within the normal laboratory range for most nonpregnant adults.

Is 100 mg/dL Normal Blood Sugar?

A fasting laboratory result of exactly 100 mg/dL falls at the beginning of the ADA prediabetes range. A nonfasting reading of 100 mg/dL cannot be classified using that same threshold.

Is 120 mg/dL High Blood Sugar?

A fasting laboratory result of 120 mg/dL falls within the prediabetes range. However, 120 mg/dL before a meal may be within the treatment target for many people already diagnosed with diabetes.

Timing and diagnosis change the interpretation.

What Is a Normal Blood Sugar Level for a 60-Year-Old?

The usual adult laboratory diagnostic thresholds still apply at age 60. Individual diabetes management targets, however, may depend on overall health and hypoglycemia risk.

Can a CGM Replace a Blood Sugar Test?

A CGM can track glucose patterns, but current ADA guidance does not support using CGM alone to diagnose prediabetes or diabetes.

Validated laboratory testing remains the standard for diagnosis.

Key Takeaways

• Normal fasting laboratory glucose is below 100 mg/dL.

• Fasting glucose of 100–125 mg/dL falls within the prediabetes range; 126 mg/dL or higher meets a diabetes diagnostic threshold when confirmed.

• A1C below 5.7% is normal, while 5.7–6.4% is within the prediabetes range.

• Age does not automatically change adult diagnostic thresholds, although diabetes treatment goals may differ.

• Blood sugar readings should always be interpreted according to the test type, timing, symptoms, and individual health circumstances.

The most useful blood sugar chart is one that matches the measurement you actually took. Understanding that distinction helps turn numbers into meaningful health information.

References

1. American Diabetes Association Professional Practice Committee. Diagnosis and Classification of Diabetes: Standards of Care in Diabetes—2026. Diabetes Care. 2026. https://doi.org/10.2337/dc26-s002

2. American Diabetes Association Professional Practice Committee. Glycemic Goals, Hypoglycemia, and Hyperglycemic Crises: Standards of Care in Diabetes—2026. Diabetes Care. 2026. https://doi.org/10.2337/dc26-s006

3. American Diabetes Association Professional Practice Committee. Older Adults: Standards of Care in Diabetes—2026. Diabetes Care. 2026. https://doi.org/10.2337/dc26-s013

4. American Diabetes Association. eAG/A1C Conversion Calculator. https://professional.diabetes.org/glucose_calc

5. Centers for Disease Control and Prevention. Treatment of Low Blood Sugar (Hypoglycemia). https://www.cdc.gov/diabetes/treatment/treatment-low-blood-sugar-hypoglycemia.html

Medical Disclaimer: This article is for general educational purposes only and does not constitute medical advice, diagnosis, or treatment. Blood glucose targets and testing needs vary by individual. Consult a qualified healthcare professional about abnormal test results, symptoms, diabetes screening, or changes to a diabetes management plan.