What Level of Blood Sugar Is Dangerous?

Spiking blood sugar levels is a common occurrence among people with type 2 diabetes. And mostly, these spikes do not cause any severe issues. However, if your blood sugar levels are higher than expected, they can lead to serious health complications.

In this article, we will examine the significance of blood sugar levels in the body, investigate different types of diabetes, and emphasise the importance of maintaining optimal blood sugar levels.

Understanding Healthy & Unhealthy Levels of Blood Sugar

Understanding Healthy & Unhealthy Levels of Blood Sugar

Diabetes is a condition that requires constant monitoring of blood sugar levels. It is important to keep your blood sugar levels in check to avoid complications. Here are some ways to define healthy blood sugar levels:

HbA1c Test

According to MedlinePlus, healthy HbA1c levels, also known as glycated hemoglobin, typically fall below 5.7%. This test measures the average blood sugar level over the past two to three months and is crucial in assessing long-term blood sugar control. Prediabetes is indicated by slightly elevated levels, with HbA1c ranging from 5.7% to 6.4%. Whereas A1c levels above 6.5% indicate diabetes.

Fasting blood sugar levels

As per the Centers for Disease Control & Prevention, healthy fasting blood sugar levels, measured after at least 8 hours of fasting, generally range between 70 and 100 milligrams per deciliter (mg/dL). Consistently higher levels may indicate prediabetes or diabetes. Fasting blood sugar levels between 100 and 125 mg/dL indicate prediabetes and values above 126 mg/dL indicate diabetes.

Random blood sugar levels

Healthy random blood sugar levels, taken at any time of the day, regardless of fasting, should typically remain below 125 mg/dL. Elevated levels may suggest diabetes or impaired glucose metabolism. Random blood sugar levels between 140 and 199 mg/dL indicate prediabetes, and values above 200 mg/dL indicate diabetes.

Glucose tolerance test

A healthy glucose tolerance test result involves blood sugar levels returning to normal ranges within two hours after consuming a standardised sugary drink. According to the National Institutes of Health, here are the typical ranges of glucose tolerance test. Typically, levels should be below 140 mg/dL after two hours. Higher readings may indicate impaired glucose tolerance or diabetes. Glucose tolerance tests that fall in the range of 140 to 199 mg/dL signify prediabetes, and GTT results above 200 mg/dL indicate diabetes.

Read More: Know What A1c Test Measures

What Is A Dangerous High Blood Sugar Level?

Blood sugar levels ranging from 180 mg/dL to 250 mg/dL indicate elevated blood glucose, termed hyperglycemia.

If the reading reaches 250 mg/dL or surpasses it, the situation becomes hazardous, necessitating immediate medical intervention.

Repeated readings of 300 mg/dL or more pose a grave risk, potentially triggering severe complications such as diabetic ketoacidosis and diabetic coma.

When blood sugar levels exceed 600 mg/dL, the condition becomes critical and life-threatening, known as hyperglycemic hyperosmolar nonketotic syndrome (HHNS).

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Symptoms of High Blood Sugar

Symptoms of High Blood Sugar

According to the Cleveland Clinic, early signs of hyperglycemia encompass:

  • Increased thirst (polydipsia) and/or hunger
  • Frequent urination (polyuria)
  • Headache
  • Blurred vision

Indications of prolonged hyperglycemia include:

  • Fatigue
  • Weight loss
  • Vaginal yeast infections
  • Skin infections
  • Delayed healing of cuts and sores

Seeking medical attention from your healthcare provider is imperative if you or your child exhibits these symptoms.

The glucose threshold at which individuals with diabetes begin to experience symptoms can vary. Many individuals remain asymptomatic until their blood sugar exceeds 250 mg/dL. Conversely, those undiagnosed with diabetes typically encounter these symptoms at lower levels.

Understanding the early indicators of hyperglycemia and routinely monitoring blood sugar levels is particularly crucial for individuals using insulin or other diabetes medications. Untreated hyperglycemia can progress to diabetes-related ketoacidosis (DKA), characterized by acidic blood due to insulin deficiency and elevated ketone levels. DKA can also affect those with undiagnosed Type 1 diabetes, posing a critical emergency that may lead to coma or death.

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Symptoms of ketoacidosis comprise:

  • Nausea and vomiting
  • Dehydration
  • Abdominal pain
  • Fruity-smelling breath
  • Deep, labored breathing or hyperventilation (Kussmaul breathing)
  • Rapid heartbeat
  • Confusion and disorientation
  • Loss of consciousness

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What Is A Dangerous Low Blood Sugar Level?

A blood sugar measurement registering at 70 mg/dL or lower signifies low blood sugar. When blood sugar dips below 50 mg/dL, it denotes severe hypoglycemia and poses significant danger. Such critically low levels constitute a medical emergency, necessitating immediate attention from a healthcare provider.

Symptoms of Low Blood Sugar

Symptoms of Low Blood Sugar

Low blood sugar affects everyone differently. It’s important to recognize your own signs. Some common symptoms include:

  • Fast heartbeat
  • Shaking
  • Sweating
  • Feeling nervous or anxious
  • Getting easily irritated or confused
  • Feeling dizzy
  • Being extra hungry

Sometimes, you might not notice any symptoms when your blood sugar is low, known as hypoglycemia unawareness. If you don’t notice these signs, it can be harder to treat low blood sugar early, which can lead to more serious lows and be dangerous.

When low blood sugar gets severe, you might experience more serious symptoms, such as:

  • Feeling weak
  • Having trouble walking or seeing clearly
  • Acting strangely or feeling confused
  • Having seizures

Read More: Can Type 1 Diabetes be Reversed With Diet and Exercise?

How To Treat High Blood Sugar In An Emergency?

If you display signs and symptoms of diabetic ketoacidosis or hyperosmolar hyperglycemic state, you may require treatment in the hospital. According to the Mayo Clinic, emergency care aims to normalize your blood sugar levels and typically includes the following:

  • Fluid replacement: Fluids, usually administered intravenously, replenish your body’s lost fluids due to excessive urination. This process also helps to dilute the excess sugar in your bloodstream.
  • Electrolyte replacement: Electrolytes are essential minerals in your blood necessary for proper tissue function. Insufficient insulin levels can lead to electrolyte imbalances. Intravenous administration of electrolytes helps maintain the normal function of your heart, muscles, and nerve cells.
  • Insulin therapy: Insulin therapy is crucial for reversing the processes that lead to ketone buildup in your blood. Alongside fluid and electrolyte replacement, insulin is typically administered intravenously.

Once your body returns to a stable state, your healthcare provider will investigate potential triggers for the severe hyperglycemia. Depending on the circumstances, further tests and treatments may be necessary.

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How To Treat Low Blood Sugar In An Emergency?

According to the CDC’s recommendation, if your blood sugar falls between 55-69 mg/dL, you can treat it using the 15-15 rule: consume 15 grams of carbohydrates and then recheck your blood sugar after 15 minutes. If it remains below your target range, repeat the carbohydrate intake. Continue this process until your blood sugar reaches the desired level. Once it’s within range, consume a balanced meal or snack to prevent it from dropping too low again.

Here are some examples of items containing approximately 15 grams of carbohydrates:

  • 4 ounces (½ cup) of juice or regular soda
  • 1 tablespoon of sugar, honey, or syrup
  • Hard candies, jellybeans, or gumdrops (refer to the food label for serving size)
  • 3-4 glucose tablets (follow package instructions)
  • 1 dose of glucose gel (usually 1 tube; follow package instructions)

Remember, it takes time for blood sugar to increase after consuming carbohydrates, so allow some time for the treatment to take effect.

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General Tips To Prevent Hyperglycemia and Hypoglycemia Episodes

Here are some simple things to take care of to help prevent hyperglycemia (high blood sugar) and hypoglycemia (low blood sugar):

  • Monitor blood sugar levels regularly with a glucose meter.
  • Maintain a balanced diet with controlled carbohydrate intake.
  • Stay physically active through regular exercise.
  • Take prescribed medications as directed by healthcare providers.
  • Be aware of symptoms and respond promptly.
  • Carry glucose tablets or snacks for hypoglycemic episodes.
  • Stay hydrated by drinking water regularly.
  • Avoid excessive alcohol consumption.
  • Communicate with healthcare providers about any changes in symptoms or medication needs.

Read More: Top 10 Early Signs and Symptoms of Diabetes


In conclusion, managing blood sugar levels is crucial for people with diabetes to prevent complications. This article has highlighted the significance of understanding blood sugar levels, types of diabetes, and the importance of maintaining optimal blood sugar levels. By monitoring blood sugar regularly, adhering to a balanced diet, staying physically active, and promptly addressing symptoms, you can effectively manage their condition. Additionally, recognizing the signs of both high and low blood sugar and knowing how to respond in emergencies are essential for maintaining overall health and well-being. Collaborating closely with healthcare providers ensures appropriate management strategies and reduces the risk of severe complications associated with blood sugar fluctuations.

Read More: Diabetes Symptoms in Men and Prevention

FAQ’s (Frequently Asked Questions)

What is the danger zone for blood sugar?

Blood sugar levels above 250 mg/dL are considered in the danger zone, indicating hyperglycemia, which can lead to serious complications if left untreated.

What are the 3 signs of hypoglycemia?

Signs of hypoglycemia include trembling or shaking, sweating, and feeling anxious or irritable.

What happens when blood sugar levels drop below 50?

Blood sugar levels below 50 mg/dL indicate severe hypoglycemia, leading to symptoms such as confusion, seizures, and loss of consciousness.

At what low blood sugar level is it dangerous?

Blood sugar levels below 50 mg/dL are considered dangerous, requiring immediate intervention to prevent severe complications.

What is the highest blood sugar level that is safe?

While individual tolerance varies, generally, blood sugar levels below 180 mg/dL are considered safe for most people with diabetes.

What to eat when blood sugar is low?

Consuming fast-acting carbohydrates like fruit juice, glucose tablets, or candy can help raise blood sugar levels quickly during a hypoglycemic episode.

What blood sugar level is alarming?

A blood sugar level exceeding 250 mg/dL is alarming, as it can lead to severe hyperglycemia and potentially dangerous complications.

What are the 3 signs of diabetic emergency?

Signs of a diabetic emergency include excessive thirst, frequent urination, and extreme fatigue.

Is 200 blood sugar very high?

Yes, a blood sugar level of 200 mg/dL is considered very high and may require immediate attention to prevent complications.

Last Updated on by Dr. Damanjit Duggal 


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