Headaches are a common medical complaint. But if you have diabetes, headaches could be a sign that your blood sugar is too high or too low.

Diabetes is a chronic metabolic disease that can cause high blood sugar. High blood sugar can lead to a host of symptoms and related complications, some of which can be life threatening. Having a headache may be a sign of high or low blood sugar.

Headaches aren’t harmful, but they can signal that your blood sugar, or glucose, is outside its target range.

If you have frequent headaches along with other symptoms of high blood sugar, such as excessive thirst and frequent urination, diabetes may be the cause.

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Headaches are one of the most common medical complaints, and they have numerous causes.

There are two types of headaches: primary and secondary.

Primary headaches occur when brain cells, nerves, blood vessels, or muscles around the head send pain signals to the brain. Primary headaches occur independently — not because of another medical condition. Migraine attacks and tension headaches are two examples.

Underlying health conditions, such as diabetes, cause secondary headaches. Other causes of secondary headaches include:

  • fever or infection
  • injury
  • high blood pressure, or hypertension
  • stroke
  • anxiety or stress
  • hormone fluctuations, such as those occurring during your menstrual cycle
  • eye disorders
  • structural abnormalities within the brain

Secondary headache causes can vary, and so can the pain they produce.

Headaches due to high blood sugar associated with diabetes often range from moderate to severe, and they occur frequently. These headaches can indicate that your glucose is too high or low.

Regulating your blood sugar may be the first step toward headache relief. Over-the-counter (OTC) pain relievers, such as acetaminophen or ibuprofen, may also help.


What makes a headache ‘severe’?



Classifying the severity of a headache isn’t always easy. Every person has a different pain tolerance. The severity of the headache is subjective and dependent on each person’s tolerance for pain. In general, doctors and other healthcare professionals will classify a headache as severe if it significantly limits a person’s ability to function normally.

Graham Rogers, MDAnswers represent the opinions of our medical experts. All content is strictly informational and should not be considered medical advice.
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Hyperglycemia occurs when a person has high blood sugar. High blood glucose levels include levels higher than 100 milligrams per deciliter (mg/dL) while fasting and greater than 140 mg/dL 2 hours after eating.

Many people don’t feel any symptoms even at higher blood sugar levels, and the symptoms are often slow to appear. A headache from high blood glucose generally takes several days of high blood sugar to develop.

Even so, headaches are considered an early sign of hyperglycemia. The pain can become more severe as your condition worsens. Also, if you have a history of hyperglycemia, a headache can be a sign to check your blood sugar.

Other early signs of hyperglycemia include:

You can manage hyperglycemia with lifestyle changes, such as regular exercise and a balanced diet. The National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) recommends eating a variety of:

  • vegetables
  • fruits
  • whole grains
  • lean protein
  • plant-based proteins, such as beans, peas, nuts, and meat substitutes
  • nonfat or low fat dairy

You can also use medications to manage your blood sugar. You’ll likely have fewer headaches when you manage your blood sugar.

Low blood glucose, or hypoglycemia, occurs when your blood sugar level is below 70 mg/dL. Unlike hyperglycemia, hypoglycemia symptoms can occur suddenly.

These symptoms can include headaches, which may seem to come out of nowhere as your blood sugar decreases. Headaches in such cases are usually accompanied by other symptoms, such as:

  • dizziness
  • shakiness
  • excessive sweating
  • sudden hunger
  • irritability
  • nausea
  • excessive fatigue
  • weakness
  • anxiety or confusion

Before you can treat a headache that occurs with these symptoms, determine whether low blood glucose is the cause with a blood glucose test.

If a blood glucose test determines your blood sugar is low, the American Diabetes Association (ADA) recommends eating 15 to 20 grams of simple carbohydrates or glucose tablets, and then checking your glucose again in 15 minutes. Once your blood sugar stabilizes, your headache may decrease.

If the pain persists, you may still need to take OTC pain relief. Call a doctor or your local emergency services immediately if your headache is severe or you can’t get your blood glucose back up.

When left untreated, hypoglycemia can lead to life threatening complications, such as seizures and coma.

Diabetes certainly isn’t the only cause of headaches. If you have diabetes, your chance of having headaches may be greater than someone without diabetes, especially if your diabetes isn’t managed effectively.

By keeping tabs on your blood glucose, you will likely have fewer headaches, as well as other diabetes symptoms. If your headaches persist despite diabetes management, you should talk with a doctor right away.

Headaches alone aren’t harmful, but they can indicate that your blood sugar is too high or low, which can be dangerous.

To find relief and avoid diabetes complications, try to keep your blood sugar levels in their target range.