What To Do If Blood Sugar Level is Above 400: Causes and Preventions

Last updated on November 2nd, 2023

Blood sugar, or glucose, serves as the primary source of energy for our bodies. For individuals with diabetes, maintaining blood sugar within a specific range is crucial to prevent complications. Uncontrolled high blood sugar, known as hyperglycemia, can lead to a range of health issues, including kidney problems, nerve damage, and heart disease.

In fact, statistics reveal that diabetic kidney disease accounts for 44% of all new cases of kidney failure in the United States. Adults with diabetes are two to four times more likely to die from heart disease than those without diabetes, as highlighted by the American Heart Association. These statistics firmly underline the critical importance of maintaining proper blood sugar levels, as it is not merely a matter of managing a condition but a decisive step toward preventing life-altering complications.

Blood Sugar Target Ranges for Diabetics

To manage blood sugar effectively, it’s essential to know your target range.

Typically, the recommended range for blood sugar levels is between 80 and 130 mg/dL before meals and below 180 mg/dL two hours after meals. A blood sugar level of 400 mg/dL is a cause for immediate concern, and understanding its implications is vital. When blood sugar reaches this level, it’s considered extremely high and well above the typical target ranges for people with diabetes. Such a high reading can have serious consequences for one’s health. 

First and foremost, a blood sugar level of 400 mg/dL is indicative of uncontrolled hyperglycemia, a state where there is an excess of glucose circulating in the bloodstream. This condition can lead to a range of short-term and long-term complications.

In the short term, immediate symptoms can include excessive thirst, frequent urination, fatigue, blurred vision, and extreme hunger. These symptoms are the body’s way of signalling that something is wrong and should not be ignored.

However, the real danger of a blood sugar level over 400 mg/dL lies in the potential for diabetic ketoacidosis (DKA). DKA is a life-threatening complication that can occur when blood sugar levels become excessively high for an extended period. When glucose cannot enter cells due to a lack of insulin or insulin resistance, the body begins to break down fat for energy. This process releases ketones into the bloodstream, making it more acidic. The result is a cascade of severe symptoms, including deep rapid breathing, a distinctive fruity odour on the breath, confusion, and even loss of consciousness.

Untreated or poorly managed DKA can have dire consequences, including severe dehydration, organ failure, and, in extreme cases, even death. This is why a blood sugar level of 400 mg/dL requires immediate attention and intervention.

Note: People with certain medical conditions may have slightly different targets, which should be discussed with the healthcare provider to ensure personalised and effective blood sugar management.

Read More: Best Diabetes Diet Plan – Dietary Guidelines For Diabetic Patients

What to Do if Blood Sugar Is 400 or Above?

If you or someone you know experiences a blood sugar reading of 400 mg/dL, it’s imperative to:

Managing High Blood Sugar Level Above 400

1. Test Again

If you get a reading above 400 mg/dL, it’s essential to test your blood sugar again to confirm the result. False readings can occur due to factors such as an issue with your testing equipment, improper testing technique, or contamination. Accurate readings are critical for taking the right steps.

2. Call Your Doctor

Once you have confirmed that the reading is accurate, contact your healthcare provider. Your doctor will provide guidance based on your specific health condition, medication, and overall well-being. It’s important to follow your doctor’s recommendations closely.

3. Test Your Urine for Ketones

Testing your urine for ketones is essential when your blood sugar is over 400 mg/dL, especially if you experience symptoms like excessive thirst, frequent urination, fatigue, or nausea. Elevated ketone levels may indicate DKA, which requires immediate attention.

4. Call for Professional Help

If your symptoms are severe you should call for professional help. Untreated hyperglycemia can result in various complications, including DKA, which can be life-threatening. If you or someone you know experiences the symptoms of DKA (discussed above), seek immediate medical attention immediately.

Read More: Can Type 2 Diabetes be Reversed Permanently?

Causes of High Blood Sugar

Understanding what can cause blood sugar spikes is crucial for effective management. Factors such as consuming high-sugar foods, missing doses of medication, or illness can lead to elevated blood sugar levels. Let’s discuss this in detail:

Causes of High Blood Sugar

1. Dietary Factors:

Nutrition plays a central role in blood sugar management. Consuming high-sugar foods and beverages, which are rapidly absorbed into the bloodstream, can cause sharp spikes in blood sugar levels. It’s important to be aware of the glycemic index (GI) of foods, as high-GI foods can lead to rapid increases in blood sugar.
For instance, a single 350ml can of regular soda can contain around 39 grams of sugar, causing a rapid blood sugar surge.

2. Medication Management:

Missing doses of prescribed medications, such as insulin or oral antidiabetic drugs, can lead to uncontrolled high blood sugar levels. This can be due to an insufficient amount of insulin or the inability of other medications to exert their intended effect.

3. Illness and Infection:

Various illnesses and infections can contribute to elevated blood sugar levels. The body’s stress response to illness often involves the release of stress hormones like cortisol, which can lead to insulin resistance. Infections, such as urinary tract infections or respiratory infections, can also trigger the release of stress hormones, causing temporary spikes in blood sugar.

4. Physical Inactivity:

Regular physical activity can improve insulin sensitivity and help manage blood sugar. Conversely, a sedentary lifestyle can contribute to high blood sugar levels. Facts show that engaging in at least 150 minutes of moderate-intensity exercise per week can significantly improve blood sugar control.

5. Stress:

Chronic stress can have a substantial impact on blood sugar levels. Stress hormones like cortisol can raise blood sugar by stimulating the liver to release glucose into the bloodstream. In fact, research suggests that stress management techniques, such as mindfulness and relaxation exercises, can help lower blood sugar levels.

6. Caffeine and Alcohol:

Both caffeine and alcohol can influence blood sugar levels. Caffeine may cause a temporary spike in blood sugar, especially in people who are not regular caffeine consumers. Alcohol, on the other hand, can cause hypoglycemia (low blood sugar) when consumed without food, but over time, excessive alcohol use can lead to hyperglycemia.

7. The Dawn Phenomenon:

The dawn phenomenon is a natural rise in blood sugar levels in the early morning hours. It occurs due to hormonal changes that increase insulin resistance. This phenomenon is more common among individuals with diabetes and often requires adjustments in medication timing or dosages to manage the elevated morning blood sugar levels effectively.

8. Uncontrolled Blood Pressure:

Hypertension (high blood pressure) is often comorbid with diabetes. Uncontrolled blood pressure can exacerbate high blood sugar levels. According to research, approximately two out of three people with diabetes also have high blood pressure, which increases the risk of heart disease and other complications.

Read More: Indian Diet for Diabetes Reversal.

Symptoms of High Blood Sugar

The following signs serve as warning signs of uncontrolled high blood sugar. Ignoring these signs can lead to serious complications, including DKA..

Symptoms of High Blood Sugar

1. Excessive Thirst (Polydipsia):

Excessive thirst is one of the hallmark symptoms of high blood sugar. When blood sugar levels rise above the normal range, the kidneys attempt to eliminate the excess glucose from the body through urine. This process requires water, leading to increased urination. To compensate for this loss of fluids, the body triggers a sensation of intense thirst. Individuals may find themselves constantly reaching for water, unable to quench their thirst, a condition known as polydipsia.

2. Frequent Urination (Polyuria):

Elevated blood sugar levels lead to excess glucose in the bloodstream, which the kidneys filter out and excrete in the urine. This excess glucose in the urine attracts water, causing increased urination. As a result, individuals experience polyuria, which can disrupt their daily routines and sleep patterns. Monitoring the frequency of urination can be a helpful way to gauge the severity of blood sugar elevation. Typically urination that amounts to more than 3L a day is categorised as polyuria.

3. Unexplained Weight Loss:

Unintended weight loss, often accompanied by increased appetite, can be a sign of high blood sugar. When blood sugar levels are elevated, the body’s cells may not receive the necessary glucose for energy due to insulin resistance or insufficient insulin production. To compensate, the body starts breaking down fat and muscle tissue for energy, leading to weight loss.

4. Blurred Vision:

High blood sugar can cause changes in the shape of the eye’s lens, affecting the ability to focus and leading to blurred vision. This symptom typically resolves once blood sugar levels are brought back into the target range.

5. Fatigue and Weakness:

Persistently high blood sugar levels can result in fatigue and weakness. Cells are not receiving the energy they need, leading to feelings of exhaustion. This can impact daily activities, productivity, and overall quality of life.

6. Fruity Breath Odour:

In severe cases, particularly when high blood sugar progresses to diabetic ketoacidosis (DKA), individuals may develop a distinctive fruity or acetone-like odour on their breath. This odour is a result of the body breaking down fat for energy and releasing ketones, which can be detected in the breath. Fruity breath odour is a critical indicator of a medical emergency, and immediate medical attention is required in such situations.

How to Prevent Hyperglycemia

  1. Limiting Sugary Beverages: Reducing or eliminating sugary beverages from your diet can help control blood sugar levels.
  2. Opting for Complex Carbohydrates: Complex carbohydrates, like whole grains and legumes, can help stabilise blood sugar and provide lasting energy.
  3. Balancing Meals: Eating balanced meals with a combination of carbohydrates, protein, and healthy fats can help control blood sugar levels.
  4. Regular Exercise: Engaging in regular physical activity can enhance insulin sensitivity and improve blood sugar control.
  5. Stress Management: Stress can impact blood sugar levels. Practising stress-reduction techniques like meditation or yoga can be beneficial.
  6. Monitoring Blood Glucose: Regularly monitoring your blood sugar levels at home is crucial for tracking your progress and making necessary adjustments.
  7. Quitting Smoking: Smoking is detrimental to overall health and can exacerbate diabetes-related complications. Quitting can improve blood sugar control and reduce health risks.

Read More: How to Stimulate Your Pancreas to produce insulin hormones in the body?


Managing high blood sugar levels, especially when they exceed 400 mg/dL, is a matter of utmost importance for diabetics. Proactive management, timely medical consultation, and a comprehensive understanding of the causes and prevention of hyperglycemia are key to maintaining good health. Don’t hesitate to consult with healthcare professionals to ensure that your blood sugar levels are well-controlled and to avoid the potential consequences of unaddressed high blood sugar.

Read More: How to Reverse Prediabetes Naturally?

FAQ (Frequently Asked Question)

At what sugar level can a diabetic coma occur?

A diabetic coma can occur at different blood sugar levels depending on the individual. However, it’s a severe complication typically associated with extremely high or extremely low blood sugar levels.

Should I take insulin for a blood sugar level over 400?

Taking insulin should be done under the guidance of a healthcare professional. Depending on your specific treatment plan, your doctor may advise you on how to manage extremely high blood sugar levels.

How long does it take for blood sugar to decrease?

The time it takes for blood sugar to decrease varies from person to person and depends on the cause of the elevated levels. Following your healthcare provider’s recommendations is essential for effective management.

Are there specific foods that can help lower blood sugar naturally?

While there’s no magical food that can drastically lower blood sugar, a balanced diet rich in fibre, whole grains, lean proteins, and plenty of vegetables can help stabilise blood sugar levels. Foods like cinnamon, fenugreek, and bitter melon may also have some beneficial effects, but it’s essential to incorporate them into a well-rounded diet.

What is the connection between blood sugar and hypoglycemia (low blood sugar)?

Hypoglycemia, or low blood sugar, is a condition characterised by blood sugar levels that are too low. It is often associated with diabetes and can result from an overdose of insulin or certain diabetes medications. The symptoms of hypoglycemia can be similar to those of high blood sugar, including sweating, shakiness, and confusion, but the causes and management strategies differ.

Is it safe to exercise with high blood sugar levels?

Engaging in physical activity with high blood sugar levels can be safe, depending on the individual and their specific circumstances. However, it’s essential to consult with your healthcare provider to determine the best approach. You may need to adjust your insulin or medication regimen and monitor your blood sugar closely before, during, and after exercise to prevent potential complications.

Last Updated on by Dr. Damanjit Duggal 


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