How Dehydration Affects Blood Glucose Levels and How to Stay Hydrated

Drinking water has many health benefits, including regulating blood sugar levels.
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Water is an essential element for everyone. After all, the human body is made up of 60 percent water, per the U.S. Geological Survey.


Not only does water help keep your organs functioning, blood pumping and skin elastic and radiant, it can also help regulate your blood-glucose levels — i.e., blood sugar.

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This means avoiding dehydration is especially important for people with diabetes who are trying to avoid high glucose levels.

Here, learn why dehydration affects your blood glucose and get tips for staying properly hydrated to keep blood sugar in check.

First, What Is Blood Glucose?

To start, it's important to know what glucose is and its role in the body.

Glucose is a form of sugar your body uses for energy. When you eat carbohydrates, your body converts carbohydrates to glucose.

Foods like refined sugar and white flour result in a greater spike in blood glucose, whereas complex carbohydrates (such as whole-grain bread) result in a slower, steadier blood-glucose rise, per the Harvard T.H. Chan School of Public Health.


As glucose levels increase, your body releases insulin, which prompts your cells to store glucose and reduces the amount in your bloodstream. Diabetes occurs when people become resistant to insulin, causing blood-glucose levels to remain high.

How Does Hydration Affect Blood Glucose?

When you are dehydrated, glucose becomes more concentrated in your blood, leading to higher blood sugar levels, per the Centers for Disease Control and Prevention (CDC).


That's why not drinking enough water can affect your blood glucose and being dehydrated can affect blood test results.

Symptoms of dehydration in adults include the following, per the Mayo Clinic:

  • Feeling extremely thirsty
  • Not peeing as often
  • Dark-colored urine (when you're hydrated, your urine should be clear or pale yellow)
  • Feeling tired
  • Dizziness
  • Confusion



On the other hand, neither dehydration nor over-hydration seem to cause or be linked to ‌low‌ blood sugar, or hypoglycemia. Low blood sugar symptoms include fast heartbeat, shaking, sweating, nervousness or anxiety, dizziness and hunger, per the CDC.

Other Causes of High Blood Glucose

Can things besides dehydration — like stress — raise blood sugar? Absolutely. A few other causes of high blood sugar include the following, per the Cleveland Clinic:


  • Autoimmune diseases (like type 1 diabetes)
  • Chronic pancreatitis
  • Pancreatic cancer
  • Cystic fibrosis
  • Lack of sleep
  • Illness or injury
  • Surgery
  • Emotional and physical stress (which increase cortisol and adrenaline levels)

How to Prevent High Blood Glucose From Dehydration

If you want to regulate your blood sugar levels through hydration, start by simply drinking water more often.


Besides helping control your blood sugar, staying hydrated helps your body distribute nutrients, eliminate waste and regulate body temperature, per the Harvard T.H. Chan School of Public Health.

Consider these tips to ensure you're properly hydrated, per the CDC:

1. Track Your Water Intake

Adults should aim to get between 11.5 and 15.5 cups of water per day through beverages containing water (drinks like seltzer, coffee and tea all count) and eating water-rich foods like fruits and vegetables, per the National Academies of Sciences, Engineering and Medicine.


Consider keeping track of how much water you're getting each day by either writing it down or using an app.


2. Carry a Water Bottle With You

Having a source of water with you at all times will make you more inclined to take sips throughout the day. Freezing a water bottle overnight and taking it with you to work or school can also encourage you to quench your thirst.

2. Choose Water Over Sugary Drinks

Opt for water over juice or soda whenever you can, as these can spike blood sugar. If you don't enjoy the taste of plain water, you can try unsweetened flavored water.

It's best to also choose water over Gatorade or other sugary sports drinks.

3. Order Water at Restaurants

While it's tempting to order that soda or glass or wine when out at a restaurant, try to opt for plain water as often as you can. Take sips throughout your meal. Drinking water with meals at home can also up your intake.

4. Add Citrus to Your Water

Another tip if you don't like the taste of plain water: Add a lemon or lime wedge to your glass. This citrus flavor is refreshing and could encourage you to drink more.

5. Drink Water While Working Out or When Outside

If you're in an environment where you sweat more (like spending time outdoors or working out at the gym), you'll need more water to replace what's been lost, per the University of Michigan.

Make sure you are also replacing essential electrolytes (which are lost through sweat), such as sodium and potassium, by adding an electrolyte drink mix to water, or reaching for coconut water, vegetable juice or bone broth occasionally.


When to See a Doctor

Even mild dehydration can throw off your normal glucose levels, resulting in high blood sugar levels.

If you already deal with high blood glucose (whether from diabetes or another underlying condition), checking your blood glucose with a monitor will tell you where your levels are at. Work with your health care provider to find the right methods to keep your glucose within your target range, such as by following a lower-carb meal plan or by taking glucose-lowering medications.

If you've never experienced high blood sugar but are exhibiting the symptoms (including increased thirst, dry mouth, needing to urinate often, blurred vision, etc., per the U.K.'s National Health Service) visit your doctor as soon as possible to get a proper diagnosis.

And if you're severely dehydrated to the point where you're dizzy, confused or have a weak or rapid pulse, go to the nearest emergency room immediately for treatment.


1. Can Dehydration Trigger Diabetes?

There is no evidence to show that chronic dehydration leads to diabetes. Rather, risk factors for type 2 diabetes include having overweight or obesity, being physically inactive and having a family member with the condition, according to the National Institute of Diabetes and Digestive and Kidney Diseases.

As we've mentioned, though, dehydration can cause a spike in blood glucose, which can worsen the symptoms of existing hyperglycemia associated with diabetes.

2. Can Dehydration Cause a Fever?

Dehydration does not cause a fever, but having a fever can lead to dehydration. The higher your fever, the more dehydrated you may become. This will also worsen if you experience vomiting and diarrhea with a fever, per the Mayo Clinic. That's why it's important to drink plenty of fluids when you have a fever.


3. Why Is My Blood Sugar High When I Have Not Eaten?

If your blood sugar is high even when you haven't eaten, you may be experiencing hyperglycemia associated with diabetes. This measure is called your "fasting blood glucose," and if it's notoriously high, it's worth bringing up to the doctor, per the Cleveland Clinic.

If you take a glucose test and your fasting blood sugar is between 100 and 125 milligrams per deciliter, it usually means you have prediabetes. If it's 126 milligrams per deciliter or higher, it typically means you have diabetes, per the Cleveland Clinic.

If you already know you have diabetes and are taking steps to manage it but your fasting blood sugar is still high, dehydration might be a factor. Per the CDC, high blood sugar can also be triggered by lack of sleep, gum disease, pain, stress and caffeine for some people. The dawn effect — a surge of hormones in the early morning — can also lead to blood sugar spikes.

4. Can Dehydration Be Mistaken for Diabetes?

The symptoms of diabetes and dehydration often overlap. The main overlapping symptoms include excessive thirst, weakness, dizziness and dry skin.

A major way to tell the difference between dehydration and diabetes, however, is the frequency with which you urinate. Most people with diabetes experience frequent urination, whereas if you're dehydrated, you're likely peeing less often and peeing in very small amounts, per the Mayo Clinic.




Is this an emergency? If you are experiencing serious medical symptoms, please see the National Library of Medicine’s list of signs you need emergency medical attention or call 911.

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