Diabetes Type 2 And Hydration

What is diabetes type 2?

Type 2 diabetes is a common chronic metabolic disorder where the level of sugar (glucose) in the blood becomes too high. Insulin is a hormone that is produced in the pancreas, it regulates blood glucose levels by allowing glucose to enter the body’s cells to be used as energy. When the pancreas cannot make enough insulin (Type 1 diabetes) or the insulin produced by the pancreas does not work effectively (Type 2 diabetes), the body can build up insensitivity to insulin, known as insulin resistance. The blood glucose causes the pancreas to continue producing insulin; however, insulin insensitivity leads to an increase in the levels of blood glucose levels in the blood.1,2

Individuals with type 2 diabetes may experience most of these symptoms: 

  • Thirst 
  • Fatigue 
  • Wounds taking longer to heal 
  • Blurred vision 
  • Weeing more than usual 
  • Regular infections (thrush)

Type 2 diabetes can be managed through healthy eating, weight loss, or staying active; however, most people will eventually need medications (eg., metformin and thiazolidinediones) to manage their type 2 diabetes to ensure their blood glucose levels are kept within a healthy range.3 However, some individuals will be required to take insulin which can be taken in the form of an insulin pen. 

The dangers of dehydration

Dehydration is usually caused by a lack of fluid intake, excessive water loss through urination, sweating, and diarrhoea, and can also be a symptom of high temperature or vomiting. There are some signs to make us aware of when our body becomes to feel dehydrated.4

For individuals with type 2 diabetes, dehydration can happen a lot easier as high levels of glucose in the blood can lead to a lack of hydration. The combination of high blood glucose levels and lack of hydration can have complications which require hospital visits. 

Below are the symptoms of dehydration

  • Tiredness.
  • Headache.
  • Thirst. 
  • Dizziness or lightheadedness. 
  • Dry mouth, eyes, or lips. 
  • The urine colour is deep yellow.4 

In some severe cases, dehydration can also lead to: 

  • Low blood pressure 
  • Lethargy 
  • Urinary problems
  • Confusion 
  • Rapid heartbeat 
  • Seizures.

Dehydration triggers the release of cortisol

Cortisol is known as the body’s stress hormone. When experiencing stress, cortisol acts on the muscles, liver, and adipose tissues, which undergo various processes and provide the body with glucose (this has associated cortisol with increased blood sugar levels).5,6

When you are dehydrated, the body is under stress and does not function as normal, which leads to the secretion of cortisol by the adrenal glands and eventually results in elevated blood glucose levels. High levels of cortisol can lead to rapid weight gain and have also been associated with a higher risk of developing type 2 diabetes.7

Cortisol levels can be controlled naturally by managing stress levels through various relaxation techniques, getting enough sleep, and ensuring a balanced diet. 

Dehydration increases blood pressure

When our blood glucose levels are elevated, the kidneys attempt to filter excess glucose from the blood and excrete it as urine. Water is removed during this process; therefore, symptoms of thirst usually arise in individuals with high blood glucose levels. Dehydration occurs when water in our bodies is not replenished, the body may even resort to other sources, such as water from the body's cells. 

Our kidneys help to regulate blood pressure and hormone levels to keep us healthy. High blood glucose levels can damage the kidney’s blood vessels causing the kidneys to work less efficiently. When the blood vessels constrict as a result of dehydration, this causes the blood pressure to increase. This can harm the kidneys and even lead to kidney failure long-term.8

Your blood volume depends on how much fluid you are taking in, if the blood volume is reduced due to dehydration, this can result in decreased blood pressure. Low blood pressure can lead to symptoms such as tiredness and dizziness, and in severe cases, may need medical treatment as it can be life-threatening.9

Staying hydrated with diabetes type 2

Water is the safest drink for people with diabetes

Our bodies are made up of around two-thirds water, hence why it is essential to continually replenish our water stores that may have been reduced throughout the day. Individuals with type 2 diabetes already have elevated blood glucose levels, consuming sweetened beverages such as fruit juice, soda, and cordial will only contribute to elevated sugar levels in the bloodstream. Drinking water helps to increase your blood volume, thus lowering your blood glucose concentration to a healthy level.10

Enough water helps manage type 2 diabetes

Drinking water can help to dilute the levels of glucose in the bloodstream, and in turn, reduce the side effects discussed above brought upon by dehydration. There are studies which showed that dehydration can deteriorate glucose regulation in individuals with type 2 diabetes and is also associated with an increased diagnosis of high blood sugar levels (hyperglycemia).11,12 


Type 2 diabetes results in elevated glucose levels in the bloodstream. This occurs when the body develops insulin resistance, and the sugar is unable to be absorbed and used by the cells resulting in the rise of sugar levels. This puts a strain on the kidneys to filter out the excess glucose and thus can lead to dehydration. Dehydration can put the body under stress, which triggers the release of cortisol in the body and can further increase the levels of glucose. It can also lead to blood vessels in the kidneys constriction, impeding kidney function and increasing blood pressure. Conversely, a lack of hydration can also reduce blood volume causing a drop in blood pressure. It is vital for individuals with type 2 diabetes to stay well hydrated and drink a minimum of 2 litres of water throughout the day to avoid health complications. 


  1. Type 2 diabetes [Internet]. Diabetes UK. [cited 2022 Oct 14]. Available from: https://www.nhs.uk/conditions/dehydration/nhs.uk/conditions/dehydration/nhttps://www.nhs.uk/conditions/dehydration/diabetes.org.uk/diabetes-the-basics/types-of-diabetes/type-2 
  2. Ahmad LA, Crandall JP. Type 2 diabetes prevention: A Review [Internet]. American Diabetes Association. American Diabetes Association; 2010 [cited 2022Nov5]. Available from: https://diabetesjournals.org/clinical/article/28/2/53/31277/Type-2-Diabetes-Prevention-A-Review  
  3. Type 2 diabetes. Diagnosis and Treatment [Internet]. Mayoclinic. 2021 [cited 2022 Oct 14]. Available from: https://www.mayoclinic.org/diseases-conditions/type-2-diabetes/diagnosis-treatment/drc-20351199
  4. Type 2 diabetes - Understanding medicine [Internet]. NHS.UK. 2017 [cited 2022 Oct 14]. Available from: https://www.nhs.uk/conditions/type-2-diabetes/understanding-medication/ 
  5. Dehydration [Internet]. NHS.UK. 2017 [cited 2022 Oct 14]. Available from: https://www.nhs.uk/conditions/dehydration/ 
  6. Thau L, Gandhi J, Sharma S. Physiology, cortisol. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2022 [cited 2022 Oct 14]. Available from: http://www.ncbi.nlm.nih.gov/books/NBK538239/ 
  7. Costello JT, Rendell RA, Furber M, Massey HC, Tipton MJ, Young JS, et al. Effects of acute or chronic heat exposure, exercise and dehydration on plasma cortisol, IL-6 and CRP levels in trained males. Cytokine [Internet]. 2018 Oct [cited 2022 Nov 5];110:277–83. Available from: https://linkinghub.elsevier.com/retrieve/pii/S1043466618300188 
  8. Joseph JJ, Golden SH. Cortisol dysregulation: the bidirectional link between stress, depression, and type 2 diabetes mellitus. Ann N Y Acad Sci [Internet]. 2017 Mar [cited 2022 Oct 14];1391(1):20–34. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5334212/ 
  9. High blood pressure & kidney disease | niddk [Internet]. National Institute of Diabetes and Digestive and Kidney Diseases. [cited 2022 Oct 14]. Available from: https://www.niddk.nih.gov/health-information/kidney-disease/high-blood-pressure 
  10. El-Sharkawy A, Sahota O, N. Lobo D. Acute and chronic effects of hydration status on health [Internet]. Oxford academic. 2015 [cited 2022 Oct 14]. Available from: https://academic.oup.com/nutritionreviews/article/73/suppl_2/97/1930742 
  11. What to drink when you have diabetes [Internet]. Diabetes UK. [cited 2022 Oct 14]. Available from: https://www.diabetes.org.uk/guide-to-diabetes/enjoy-food/what-to-drink-with-diabetes 
  12. Seal AD, Suh HG, Jansen LT, Summers LG, Kavouras SA. Chapter 11 - hydration and health. In: Pounis G, editor. Analysis in Nutrition Research [Internet]. Academic Press; 2019 [cited 2022 Oct 14]. p. 299–319. Available from: https://www.sciencedirect.com/science/article/pii/B9780128145562000117 
  13. Johnson EC, Bardis CN, Jansen LT, Adams JD, Kirkland TW, Kavouras SA. Reduced water intake deteriorates glucose regulation in patients with type 2 diabetes. Nutr Res. 2017 Jul;43:25–32.

Darija Golubovic

Bachelor's degree, Nutrition Sciences, The Manchester Metropolitan University, England

I graduated from Manchester Metropolitan University with a First Class in Nutritional Science BSc.
I aim to continue promoting health, wellbeing and fitness and influencing healthy food choices and sustainability.
Registered Associate Nutritionist delivering the NHS Diabetes Prevention Programme.

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