Man with headache checking for high blood sugar with glucometer

Can high blood sugar cause headaches?

Medically reviewed on October 19, 2022 by Jordan Stachel, M.S., RDN, CPT. To give you technically accurate, evidence-based information, content published on the Everlywell blog is reviewed by credentialed professionals with expertise in medical and bioscience fields.

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Sometimes, your headache might simply result from stress related to the deadlines and to-do lists on your plate. However, repeated headaches after eating may be a sign of a separate condition—high blood sugar.

Blood sugar is an important factor in your health. The blood carries glucose, or sugar, throughout the body to give you energy. But if blood sugar is too low or too high, you can suffer from related health symptoms, including headaches. So, can stress raise blood sugar? High stress levels can affect how the body regulates glucose and increase the levels.

If you suspect headaches are a symptom of blood sugar issues, it’s important to understand how they are related—and whether your high or low blood sugar levels could be linked to another health issue, like type 1 or type 2 diabetes.

Blood sugar and your body

Before diving into headaches and abnormal blood sugar levels, it’s important to understand what blood sugar means.

Your blood sugar measures the amount of glucose present in the bloodstream. This sugar molecule is the body’s main source of energy, fueling every single organ and cell in the body. And to get this fuel, you need to eat.

Every glucose molecule you receive comes straight from diet or from stored energy. To turn food into energy, your body processes blood sugar through these steps:

  1. Consumption – foods are composed of three macronutrients—carbohydrates, proteins, and fats, and different foods provide different macronutrient amounts depending on the type of foods consumed. Carbohydrates (like bananas or rice) are your body’s main source of energy as they are broken down into glucose. Simple carbohydrates (like sugar and white flour) break down more easily, creating higher spikes in blood sugar.
  2. Digestion – Once consumed, the enzymes and acids in your digestive system immediately start breaking down carbohydrates into glucose. This glucose is then released into your bloodstream.
  3. Insulin release – After digestion, the added glucose in the bloodstream triggers the pancreas to release insulin. This hormone tells the body’s cells to absorb glucose, either immediately using it as energy or storing it in your muscles as glycogen. Once glucose returns to normal levels in the bloodstream, the pancreas lowers insulin production.

Diabetes and blood sugar

In a healthy person, blood sugar hovers between 70 to 140 mg/dL, usually staying below 99 mg/dL when fasting. However, certain health conditions can push blood sugar outside of this window—particularly diabetes.

Diabetes is a metabolic condition in which your body fails to make enough insulin or has less sensitivity to insulin release. As a result, the body can become hyperglycemic, the medical term for high blood sugar (and levels can rise up to 180 mg/deciliters or higher). [1]

While all diabetics are susceptible to hyperglycemia, the cause of this issue differs between each type:

  • Type 1 diabetes, a genetic autoimmune condition often diagnosed in children and teens
  • Type 2 diabetes, a developed metabolic reaction that may result from a combination of genes, diet, and lifestyle
  • Gestational diabetes, a temporary metabolic condition that occurs during pregnancy

Blood sugar and headaches—the connection

Think of blood glucose levels as a scale. Go too low or too high, and your entire body is thrown off balance—and the first warning sign just might be a headache.

Headaches are a very common symptom among adults. In fact, almost half the adult population has at least one headache per year. [2] Medically, headaches can be broken down into two types:

  1. Primary headaches, which occur when the nervous system directly sends pain signals to the brain (such as a migraine headache).
  2. Secondary headaches, which occur when indirect health conditions (such as diabetes, injuries, or stress) create referred pain in the cranial area.

Hyperglycemia is a cause of secondary headaches. When blood sugar levels rapidly rise, they can create headache pain via:

  • Hormonal shifts – Excess glucose in the bloodstream can trigger shifts in hormones such as epinephrine and norepinephrine. These hormones directly impact the constriction of the blood vessels in the brain, which can cause headaches. [3]
  • Dehydration – When insulin fails to clear glucose from your body, it makes a last-ditch effort to urinate it out. However, excess urination (a diabetes symptom) can leave you dehydrated. Dehydration shrinks bodily tissues like your brain by reducing water content, which can put excess pressure on the nerves and create a headache. [4]

For many hyperglycemia sufferers, a headache is the first symptom to appear. However, high blood sugar doesn’t always create symptoms, even at higher levels above 180 mg/dL. [5] It can take days or weeks of chronic high blood sugar levels to develop hyperglycemia symptoms.

Other symptoms of high blood sugar

When dealing with high blood sugar, the key is to pay attention to your symptoms and act quickly. The longer you suffer from hyperglycemia, the more likely you’ll develop serious symptoms. [6] Continuous high blood sugar issues may also indicate that you have or are at risk of developing type 2 diabetes.

Chronic post-meal headaches are usually the first sign of hyperglycemia. However, you should also keep watch for other signs that your blood sugar remains too high, such as:

  • Frequent urination
  • Increased thirst
  • Extreme hunger
  • Fruity or sweet-smelling breath
  • Blurry vision
  • Numbness or tingling in the hands or feet
  • Fatigue
  • Dry skin
  • Sudden weight loss

Manage your metabolic health with Everlywell

Curious if that headache is just a result of some tension—or something more? Our team can help you find out. If you suspect diabetes or metabolic conditions might affect your health, the Everlywell At-Home HbA1c Test can lend a guiding hand.

By learning about the prediabetic range of HbA1c levels and measuring HbA1c levels, our test evaluates your blood sugar levels over the past three months. This marker gives a more effective evaluation of your health than a singular blood glucose level measurement, pointing to any long-term metabolic issues.

If you’re ready to protect your metabolic health, learn more about our HbA1c at-home test today.

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  1. CDC. Diabetes Tests. Published 2019. URL. Accessed September 30, 2022.
  2. World Health Organization: WHO. Headache disorders. Published April 8, 2016. URL. Accessed September 30, 2022.
  3. Wei X, Yan J, Tillu D, et al. Meningeal norepinephrine produces headache behaviors in rats via actions both on dural afferents and fibroblasts. Cephalalgia. 2015;35(12):1054-1064. doi:10.1177/0333102414566861. Accessed September 30, 2022.
  4. Dehydration Headache: Dehydration Symptoms & Types of Headaches. Cleveland Clinic. URL. Accessed September 30, 2022.
  5. Mayo Clinic. Hyperglycemia in diabetes - Symptoms and causes. Published 2018. URL. Accessed September 30, 2022.
  6. Centers for Disease Control and Prevention. Blood Sugar and Diabetes. Published 2019. URL. Accessed September 30, 2022.
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