How Dehydration May Affect Type 2 Diabetes Management and Risk
Updated on April 24, 2026
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Dehydration feels rotten. Not only do we feel sluggish and cranky when we don’t get enough water — our bodies also can’t circulate enough blood to the brain, kidneys, and muscles when it occurs, says Robert Rizza, MD, an emeritus professor of medicine at Mayo Clinic College of Medicine and Science in Rochester, Minnesota.
If you have type 1 or type 2 diabetes, even mild dehydration can pose additional issues. It can lead to blood sugar spikes and make daily management more difficult. Getting to know dehydration’s risks and how to stay hydrated can help you stay healthy and avoid complications.
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How Dehydration Makes It Harder to Control Blood Sugar
Dehydration can create a cycle that makes diabetes more difficult to manage.
When there is less water in your body, there’s less liquid in your bloodstream. This can cause glucose to concentrate more in your blood, leading to high blood sugar levels.
Your body may react by releasing hormones that also raise blood sugar. These include arginine vasopressin, which tells your liver to release glucose and causes the kidneys to retain more water, as well as the stress hormones cortisol and epinephrine, which increase the amount of glucose that your body produces, Dr. Rizza says. Arginine vasopressin also can increase insulin resistance, which may push blood sugar higher.
When this causes consistently high blood sugar, you will often need to go to the bathroom more because your kidneys will start to spill excess blood sugar into your urine, pulling excess water with it. This keeps the dehydration cycle going and makes blood sugar that much harder to control.
Left untreated, high blood sugar or hyperglycemia can cause symptoms that include:
- Headaches
- Blurred vision
- Trouble healing
- Weight loss
- Fatigue
- Skin infections
It also can lead to a dangerous condition called diabetic ketoacidosis, in which your blood becomes acidic, as well as hyperosmolar hyperglycemic syndrome, in which high blood sugar leads to extreme dehydration. If you have symptoms of these diabetic emergencies, such as fruity-smelling breath or loss of consciousness, seek immediate medical attention.
Can Dehydration Affect Type 2 Diabetes Risk?
Although dehydration can raise your blood sugar and lead to serious health issues if you have diabetes, it is unclear whether chronic dehydration increases your risk of developing prediabetes and type 2 diabetes. In fact, people who do not have diabetes may not see the same blood sugar spikes if they are dehydrated.
“There have been a variety of things dehydration has been suggested to contribute to, but not diabetes,” Rizza says.
How much water you drink certainly doesn’t affect your risk of developing type 2 diabetes as much as other risk factors, such as your age, body weight, physical activity, diet, and overall health.
But higher levels of copeptin, a blood marker that reflects levels of the hormone vasopressin, which rises when you’re dehydrated, are linked to lower fluid intake and a greater risk of type 2 diabetes.
If you have type 2 diabetes, drinking water before meals can reduce your fasting blood sugar, body weight, and copeptin levels, in addition to reducing your dehydration risk.
How to Stay Hydrated if You’re Managing Type 2 Diabetes
Staying hydrated is important for maintaining your health, and it’s especially important if you have diabetes.
Tips to ensure that you’re getting enough water include:
- Have some salt — but not too much. Too much salt can be bad for your blood pressure, Rizza says, but you do need some to maintain proper hydration. When you eat salt, it helps to stabilize your electrolytes, which are charged substances that regulate essential functions in your body, helping you stay hydrated. If you already have high blood pressure, talk with your doctor about how much salt to consume.
- Check your blood glucose levels when in extreme heat, and drink water if they are elevated. When it’s hot, it’s easier to become dehydrated. “Staying well hydrated can help reduce your blood glucose levels, which helps you manage the hormone insulin,” says Anna Simos, MPH, a certified diabetes care and education specialist with the Stanford Health Care Diabetes Education and Prevention Program in Palo Alto, California. And make sure that your blood glucose test strips and insulin are stored in a cool, dry place, she says, so that they don’t lose their potency and accuracy.
- Drink water regularly. Consider drinking a glass of water as soon as you wake up and before each meal. How much water you need each day can vary based on your condition. Talk to your doctor about what’s best for you.
- Reach for hydrating snacks if you’re hungry. For example, choose a cold piece of melon or a few frozen grapes, Simos says. Drinking a glass of water isn’t the only way to get your fix.
- Above all, pay attention to your thirst signals. These include feeling tired, having darker urine, experiencing muscle cramps, and having dry mouth. Ultimately, ensuring that you’re well hydrated will help you better manage type 2 diabetes, Simos says. “If you’re already dehydrated, you’re going to be prone to having high blood sugar because you don’t have as much fluid running around in your blood to hydrate and keep that equilibrium with glucose molecules,” she says.
Resources We Trust
- Mayo Clinic: Hyperglycemia in Diabetes
- American Diabetes Association: Why You Should Drink More Water
- Johns Hopkins Medicine: Dehydration and Heat Stroke
- MedlinePlus: Fluid and Electrolyte Balance
- University of Maryland Medical System: Staying Hydrated When You Have Diabetes
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Resources
- Staying Hydrated When You Have Diabetes. University of Maryland Medical System.
- Szczepanska-Sadowska E et al. Molecular Interaction Between Vasopressin and Insulin in Metabolic Regulation. International Journal of Molecular Sciences. December 10, 2024.
- Koceva A et al. The Impact of Hydration on Metabolic Outcomes. Medicina. May 1, 2025.
- Hyperglycemia in Diabetes. Mayo Clinic. April 5, 2023.
- Hyperglycemia (High Blood Sugar). Cleveland Clinic. March 2, 2023.
- Hyperosmolar Hyperglycemic State (HHS). Cleveland Clinic. February 17, 2023.
- Carroll HA et al. Effect of Acute Hypohydration on Glycemic Regulation in Healthy Adults: A Randomized Crossover Trial. Journal of Applied Physiology. February 1, 2019.
- Carroll HA et al. The Association Between Water Intake and Future Cardiometabolic Disease Outcomes in the Malmö Diet and Cancer Cardiovascular Cohort. PLOS One. January 19, 2024.
- Enhörning S et al. Investigation of Possible Underlying Mechanisms Behind Water-Induced Glucose Reduction in Adults With High Copeptin. Scientific Reports. December 29, 2021.
- Janbozorgi N et al. Water intake and risk of type 2 diabetes: A systematic review and meta-analysis of observational studies. Diabetes & Metabolic Syndrome: Clinical Research & Reviews. July–August 2021.
- Fluid and Electrolyte Balance. MedlinePlus. May 16, 2024.
- Dehydration and Heat Stroke. Johns Hopkins Medicine.
- Why You Should Drink More Water. American Diabetes Association.