Blood sugar, also known as blood glucose, is the main type of sugar found in the blood. It is the body’s main source of energy and is essential for the proper functioning of the brain and other organs. The level of blood sugar in the body is regulated by the hormone insulin, which is produced by the pancreas.
Normal blood sugar levels for a healthy adult are typically between 70 and 100 mg/dL (milligrams per deciliter) when fasting (before eating), and less than 140 mg/dL two hours after a meal. However, these values may vary depending on the person, time of day, and other factors.
People with diabetes, a chronic condition characterized by high levels of sugar in the blood, have difficulty regulating their blood sugar levels. They may need to monitor their blood sugar levels regularly and take medications or make lifestyle changes to manage the condition.
What level of blood sugar is dangerous?
Blood sugar levels that are too high or too low can be dangerous.
Hyperglycemia, or high blood sugar, is a common complication of diabetes and can occur when the body is unable to produce enough insulin or when the insulin that is produced does not work properly. High blood sugar levels can cause symptoms such as increased thirst, frequent urination, blurred vision, and fatigue. If left untreated, it can lead to serious complications such as heart disease, stroke, and nerve damage.
A dangerously high blood sugar level is considered to be above 600 mg/dL. At this level, the body can no longer effectively remove the sugar through urine and is at risk of developing ketoacidosis, a condition characterized by high levels of ketones (byproducts of fat breakdown) in the blood, which can lead to a coma or even death.
Hypoglycemia, or low blood sugar, can occur when a person with diabetes takes too much insulin or oral diabetes medications or skips a meal. Low blood sugar can cause symptoms such as sweating, shaking, confusion, and weakness. A dangerously low blood sugar level is considered to be below 70 mg/dL. At this level, the brain is not getting enough glucose, which can lead to seizures, unconsciousness, or even death if not treated promptly.
Normal blood sugar level charts

Normal blood sugar levels can vary depending on a number of factors, including the time of day and when the last meal was consumed. However, generally, the following ranges are considered normal for blood sugar levels:
- Fasting blood sugar: 70-100 mg/dL (milligrams per deciliter)
- Blood sugar 1-2 hours after a meal: Less than 140 mg/dL
It’s worth noting that these values may vary depending on the person and the laboratory that performs the test. Also, for those without diabetes, blood sugar levels can fluctuate during the day and night.
For people with diabetes, it’s important to consult with a doctor to determine what are the normal levels for them and to establish a target range for blood sugar control. These targets may be different for each individual and can be affected by various factors such as medication, diet, exercise, stress, and illness, among others.
Blood sugar symptoms
Symptoms of high blood sugar (hyperglycemia) can include:
- Increased thirst
- Frequent urination
- Blurred vision
- Fatigue
- Slow healing of cuts and wounds
- Dry, itchy skin
- Weight loss
- Nausea and vomiting (in severe cases)
Symptoms of low blood sugar (hypoglycemia) can include:
- Sweating
- Shaking
- Confusion
- Weakness
- Hunger
- Dizziness
- Difficulty speaking
- Numbness or tingling in the mouth or lips
- Headache
Why blood sugar is important?
Blood sugar, also known as blood glucose, is important for the body’s overall health because it is the primary source of energy for the body’s cells, including the brain. The body uses glucose from the blood to fuel all of its functions, from physical activity to thinking and decision-making.
The body regulates blood sugar levels through the hormone insulin, which is produced by the pancreas. Insulin helps the body’s cells absorb glucose from the bloodstream, thus maintaining normal blood sugar levels.
When blood sugar levels are too high or too low, it can cause serious health problems. High blood sugar levels (hyperglycemia) can lead to diabetes and its complications, such as heart disease, stroke, nerve damage, kidney damage, eye damage, and amputations. Low blood sugar levels (hypoglycemia) can cause symptoms such as sweating, shaking, confusion, and weakness and can lead to seizures, unconsciousness, or even death if not treated promptly.
Maintaining normal blood sugar levels is also important for overall health. Consistently high or low blood sugar levels can affect the immune system, increase the risk of infections and make it harder for the body to heal wounds.
What is normal blood sugar by age?
Normal blood sugar levels can vary depending on a person’s age. Generally, the following ranges are considered normal for blood sugar levels:
- Children and infants:
- Fasting blood sugar: 70-100 mg/dL (milligrams per deciliter)
- Blood sugar 1-2 hours after a meal: Less than 140 mg/dL
- Adults:
- Fasting blood sugar: 70-100 mg/dL
- Blood sugar 1-2 hours after a meal: Less than 140 mg/dL
- Elderly:
- Fasting blood sugar: 70-100 mg/dL
- Blood sugar 1-2 hours after a meal: Less than 140 mg/dL
The medical term for blood sugar test
The medical term for a blood test that measures the level of glucose (sugar) in the blood is a “glucose tolerance test” or “blood glucose test”. It can also be referred to as a “blood sugar test” or “glucose test”. The most common blood glucose test is the “fasting blood glucose test”, which measures the level of glucose in the blood after an overnight fast. Other tests include the “random blood glucose test” which measures glucose level at any time during the day, and the “oral glucose tolerance test” which measures glucose level after drinking a sweetened liquid. These tests can help diagnose diabetes and monitor glucose levels in people with diabetes.
How to manage blood sugar?

Managing blood sugar involves maintaining healthy levels of glucose in the blood. There are several ways to do this, including:
- Eating a healthy diet: Eating a diet that is high in fruits, vegetables, and lean proteins and low in processed foods, sugar, and saturated fat can help keep blood sugar levels stable.
- Exercising regularly: Regular physical activity can help the body use insulin more effectively and can lower blood sugar levels.
- Monitoring blood sugar levels: People with diabetes should check their blood sugar levels regularly to ensure they are within their target range.
- Medications: People with diabetes may need to take medications such as insulin or oral diabetes medications to help regulate their blood sugar levels.
- Reducing stress: High levels of stress can raise blood sugar levels, so finding ways to manage stress, such as through exercise, meditation, or therapy, may help.
- Regular check-up: It’s important to consult with a doctor regularly to monitor blood sugar levels and to adjust treatment if necessary.
- Quit smoking and limit alcohol consumption: Both smoking and excessive alcohol consumption can affect the body’s ability to regulate blood sugar levels.