Blood Sugar Levels Chart by Age: Normal, Prediabetes & Diabetes Ranges
Understanding your blood sugar levels by age can help you make sense of glucose test results and recognize when you may need medical advice. However, there is an important point that is often misunderstood: normal blood sugar does not simply increase as you get older. The blood glucose levels used to diagnose prediabetes and diabetes are generally based on the type of test rather than age alone.
What can change with age is the recommended blood sugar target for someone who already has diabetes. Older adults may have different treatment goals depending on their overall health, other medical conditions, risk of low blood sugar, and ability to manage diabetes safely.
In this guide, we explain blood sugar levels by age, fasting and after-meal glucose ranges, normal and prediabetes levels, diabetes diagnostic values, blood sugar targets for people with diabetes, children's and older adults' considerations, pregnancy-related targets, and when high or low blood sugar requires medical attention.
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Blood sugar interpretation depends on the type of test,
diabetes status, pregnancy, and individual health factors—not age alone. |
Blood Sugar Levels Chart by Age: Quick Overview
The table below gives a practical overview of commonly used blood glucose ranges. It is important to understand that the normal, prediabetes, and diabetes diagnostic ranges are not simply changed according to age. The values depend mainly on the test being performed and whether the person is pregnant.
| Group or Situation |
Fasting Blood Sugar |
Before Meals |
After Meals |
| Non-pregnant adults without diabetes |
Below 100 mg/dL is generally normal |
Not usually used as a diagnostic category |
Depends on the test; 2-hour OGTT below 140 mg/dL is normal |
| Prediabetes |
100–125 mg/dL |
Not applicable as a separate diagnostic range |
2-hour OGTT: 140–199 mg/dL |
| Diabetes diagnostic range |
126 mg/dL or higher |
Not applicable as a separate diagnostic range |
Random glucose 200 mg/dL or higher with symptoms may indicate diabetes |
| Many non-pregnant adults with diabetes |
Individual target |
80–130 mg/dL is a common target |
Below 180 mg/dL about 1–2 hours after the beginning of a meal |
These values are general medical guidelines, not personal treatment instructions. A laboratory diagnosis of diabetes generally requires confirmation when the person does not have clear symptoms. Home glucose meter readings are useful for monitoring but should not be used alone to diagnose diabetes. For more information about diabetes testing and diagnosis, see the National Institute of Diabetes and Digestive and Kidney Diseases guide to diabetes tests and diagnosis.
Does Normal Blood Sugar Change With Age?
One of the most common questions is whether older adults are supposed to have higher "normal" blood sugar than younger adults.
The answer is not necessarily.
For diagnosing prediabetes and diabetes in non-pregnant adults, the commonly used fasting blood glucose cutoffs remain:
- Normal: 99 mg/dL or below
- Prediabetes: 100–125 mg/dL
- Diabetes: 126 mg/dL or higher
These diagnostic categories are not automatically raised simply because a person is older.
However, the situation is different for people who already have diabetes. Their individual blood sugar goals may be adjusted according to age, general health, other medical conditions, cognitive function, treatment complexity, and risk of hypoglycemia.
Therefore, it is more accurate to say that diabetes treatment targets may be individualized with age, rather than saying that normal blood sugar naturally becomes higher with age.
Normal Blood Sugar Levels for Children and Teenagers
Children and teenagers can develop diabetes, and blood glucose testing may be recommended when symptoms or risk factors are present.
For children without diabetes, normal blood glucose values are generally interpreted using the same basic principles of glucose testing, although the healthcare professional will consider the child's age, clinical condition, symptoms, and the type of test performed.
Parents should not assume that a child's blood sugar is normal simply because the child is young. Symptoms such as increased thirst, frequent urination, unexplained weight loss, extreme tiredness, or new bed-wetting in a previously toilet-trained child should be discussed with a healthcare professional.
Children with diabetes may have individualized glucose targets. These targets can depend on age, developmental stage, type of diabetes, treatment plan, and risk of hypoglycemia.
Parents and caregivers should follow the glucose targets provided by the child's diabetes care team rather than using a generic online chart to change medication doses.
Normal Blood Sugar Levels for Adults
For non-pregnant adults who do not have diabetes, a fasting plasma glucose level of 99 mg/dL or below is generally considered normal.
A fasting result between 100 and 125 mg/dL falls into the prediabetes range, while a fasting result of 126 mg/dL or higher is within the diabetes range used for diagnosis.
However, a single abnormal result does not always establish a diagnosis. If a person does not have clear symptoms of diabetes, healthcare professionals generally use repeat testing or another accepted diabetes test to confirm the diagnosis.
Other tests may include an A1C test, a 2-hour oral glucose tolerance test, or a random plasma glucose test when appropriate. The CDC's diabetes testing information also explains how different blood glucose tests are used to identify prediabetes and diabetes.
If you want to understand long-term blood sugar control, read our guide to the HbA1c test, normal range, and results.
Blood Sugar Targets for Adults With Diabetes
The blood sugar range used to diagnose diabetes is not the same as the daily target range used by someone who already has diabetes.
For many non-pregnant adults with diabetes, commonly used glucose targets are:
| Time of Testing |
Common Target for Many Adults With Diabetes |
| Before a meal |
80–130 mg/dL |
| About 1–2 hours after starting a meal |
Below 180 mg/dL |
| HbA1c for many adults |
Below 7% |
These are general targets and are not appropriate for every person. Your healthcare professional may recommend different goals based on your age, health status, medications, risk of hypoglycemia, and other individual factors.
For more detailed information about managing blood glucose, you can refer to the American Diabetes Association information on checking blood sugar.
For people living with Type 2 Diabetes, regular monitoring and a personalized treatment plan are important for long-term health.
It is also important to remember that an HbA1c result and a home glucose reading provide different information. HbA1c reflects average blood glucose over approximately three months, while a glucose meter shows your blood sugar at a particular moment.
Fasting Blood Sugar Levels by Age
A fasting blood sugar test measures glucose after you have not eaten for at least 8 hours. Water is generally allowed during the fasting period.
For non-pregnant adults, the commonly used diagnostic categories are:
| Fasting Blood Sugar |
General Interpretation |
| Below 100 mg/dL |
Normal |
| 100–125 mg/dL |
Prediabetes range |
| 126 mg/dL or higher |
Diabetes range for diagnosis |
These values are used for laboratory diagnosis and do not mean that every home glucose reading in these ranges automatically confirms a medical condition.
For example, a person may occasionally have a higher fasting glucose level because of illness, stress, poor sleep, medication effects, or other factors. Your healthcare professional will interpret the result in context.
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A fasting blood glucose test measures blood sugar
after a period without food and is commonly used
to screen for and diagnose diabetes. |
Blood Sugar Levels After Eating
Blood glucose normally rises after eating because carbohydrates are broken down into glucose and absorbed into the bloodstream.
For many non-pregnant adults who already have diabetes, the commonly used target is below 180 mg/dL approximately 1–2 hours after the beginning of a meal.
This target is different from the 2-hour oral glucose tolerance test used for diagnosing diabetes and prediabetes. In an oral glucose tolerance test, the person drinks a measured glucose solution under controlled conditions. A 2-hour value below 140 mg/dL is generally considered normal, 140–199 mg/dL is in the prediabetes range, and 200 mg/dL or higher is in the diabetes range.
Therefore, you should not confuse a routine post-meal home glucose target with the diagnostic result from a formal oral glucose tolerance test.
Food choices, portion sizes, physical activity, medications, stress, sleep, and illness can all influence post-meal glucose levels.
For practical nutrition guidance, our article on healthy eating for weight loss discusses balanced eating habits that can also support better metabolic health.
The Mayo Clinic's information about diabetes management also highlights the importance of monitoring blood sugar, following a balanced eating plan, staying physically active, and working with your healthcare team.
Blood Sugar Levels in Older Adults
Older adults should not assume that high blood sugar is a normal part of aging.
Persistent high blood glucose can still increase the risk of complications involving the heart, blood vessels, kidneys, nerves, eyes, and other organs.
At the same time, diabetes treatment in older adults often requires a more individualized approach. Some older people have multiple medical conditions, take several medications, or have a higher risk of hypoglycemia. For them, a very aggressive glucose-lowering plan may not always be appropriate.
Healthcare professionals may therefore individualize glucose and HbA1c targets according to:
- Overall health and life expectancy
- Existing diabetes complications
- Risk of low blood sugar
- Other medical conditions
- Cognitive and functional health
- Current diabetes medications
- Ability to safely manage treatment
The key message is simple: older age does not automatically make a high blood sugar level normal. Instead, the treatment goal may be adjusted to balance the benefits of glucose control with the risks of treatment.
Blood Sugar Levels During Pregnancy
Pregnancy requires special consideration because blood glucose targets can differ from those used for non-pregnant adults.
For many pregnant women with diabetes, commonly recommended targets include:
| Timing |
Common Pregnancy Target |
| Fasting |
70–95 mg/dL |
| 1 hour after eating |
Below 140 mg/dL |
| 2 hours after eating |
Below 120 mg/dL |
Pregnancy-related glucose targets should always be discussed with the obstetric and diabetes care team because individual recommendations may vary.
Gestational diabetes is diagnosed using specific pregnancy-related testing protocols. A normal blood sugar chart for non-pregnant adults should not be used to interpret pregnancy glucose tests.
The NHS guidance on gestational diabetes provides additional information about blood glucose testing and diabetes during pregnancy.
Prediabetes vs Diabetes: Blood Sugar Diagnostic Chart
Understanding the difference between prediabetes and diabetes is essential because the ranges are close but have different clinical meanings.
| Test |
Normal |
Prediabetes |
Diabetes |
| Fasting plasma glucose |
99 mg/dL or below |
100–125 mg/dL |
126 mg/dL or higher |
| A1C |
Below 5.7% |
5.7–6.4% |
6.5% or higher |
| 2-hour oral glucose tolerance test |
Below 140 mg/dL |
140–199 mg/dL |
200 mg/dL or higher |
| Random plasma glucose |
Not used for diagnosis |
Not used for diagnosis |
200 mg/dL or higher with classic symptoms |
These diagnostic ranges apply to non-pregnant individuals. Diabetes diagnosis generally requires appropriate confirmation unless symptoms and test results clearly establish the diagnosis.
If your blood sugar results fall into the prediabetes range, it does not necessarily mean that you will develop diabetes. Lifestyle changes, weight management, physical activity, and medical follow-up can help reduce future risk.
You can learn more about sustainable weight management in our guide on how to lose weight and keep it off.
For additional information about preventing or delaying type 2 diabetes, the CDC's National Diabetes Prevention Program resources explain how lifestyle changes can help reduce diabetes risk in people with prediabetes.
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Common diagnostic ranges for fasting glucose
and A1C in non-pregnant adults. |
What Is Low Blood Sugar?
Low blood sugar, also called hypoglycemia, is generally defined as a blood glucose level below 70 mg/dL for many people with diabetes.
Possible symptoms include:
- Shaking or trembling
- Sweating
- Hunger
- Fast heartbeat
- Dizziness
- Weakness
- Confusion
- Irritability
Severe hypoglycemia can cause seizures, loss of consciousness, or other serious complications.
If you have diabetes and experience repeated low blood sugar readings, contact your healthcare team. Your medications, food intake, physical activity, alcohol use, or other factors may need to be reviewed.
If a person is unconscious or unable to swallow safely, do not give food or drink by mouth. Emergency medical assistance should be obtained immediately.
The CDC's guidance on treating low blood sugar explains the symptoms of hypoglycemia and the recommended immediate response for people who are able to safely consume carbohydrates.
What Causes High Blood Sugar?
High blood sugar, or hyperglycemia, can occur for many reasons.
Common causes include:
- Eating more carbohydrates than planned
- Missing or delaying diabetes medication
- Insufficient physical activity
- Illness or infection
- Physical or emotional stress
- Certain medications
- Insufficient insulin production or action
Long-term high blood sugar can contribute to diabetes complications, which is why regular monitoring and appropriate medical care are important.
People with excess abdominal fat may also have increased insulin resistance. Our article on belly fat and high blood pressure explains how metabolic health and cardiovascular risk can be connected.
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Balanced nutrition, regular physical activity, healthy weight management,
and appropriate medical care can support better blood sugar control. |
