What is the Difference Between Diabetes Mellitus and Diabetes Insipidus?

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You must have heard about “Diabetes”. But do you know the exact difference between diabetes mellitus and diabetes insipidus

Many people relate the first word, “Diabetes”, with high sugar levels, but that’s not true. 

Diabetes mellitus is generally associated with high sugar levels in your blood. While diabetes insipidus is not related to blood glucose

Although these diseases share the first name and few symptoms. This is only a similarity but diabetes mellitus and insipidus are entirely different diseases. 

In this post, I will explain the difference between diabetes mellitus and diabetes insipidus

Let’s discuss this in detail. 


What is diabetes meaning exactly? How do I know whether I have diabetes mellitus or diabetes insipidus?

The “Diabetes” word has been taken from the Greek language word “Siphon”. It means Passing excessive amount of urine“. In other words, a large discharge of urine from your body. 

In Diabetes, you will have frequent urination in excessive amounts. This is called Polyuria. Due to this polyuria, your body gets dehydrated and you will have intense thirst. This excessive thirst is called Polydipsia

The polyuria and polydipsia are prevalent symptoms in both diabetes. 

difference between diabetes mellitus and diabetes insipidus

Suppose you get the urine tested and find glucose (or glucosuria) in your urine report indicating Diabetes Mellitus. 

Here, “Mellitus” is a Latin word that means “Honey” or “Sweet.” In this condition, you may get sweet-smelling urine with Polyuria.  

Conversely, if you don’t find glucose (or glucose absent) in your urine report but heavy urination, that indicates Diabetes Insipidus.  

The “Insipidus” is also from a Latin word that means “tasteless.” In this condition, you may get non-sweet-smelling urine with Polyuria.  

Excessive urine + sweet smell urine (Glucose present) → Diabetes Mellitus

Excessive urine + non-sweet smell urine (Glucose absent) → Diabetes Insipidus

difference between diabetes mellitus and diabetes insipidus



What is the exact difference between diabetes mellitus and diabetes insipidus?

Diabetes mellitus and diabetes insipidus seem similar but are two different diseases. Let’s understand one by one and know the main difference between diabetes mellitus and diabetes insipidus.  

Diabetes Insipidus 

Diabetes Insipidus is not a common disease like diabetes mellitus. 

You cannot find the diabetes insipidus patient easily. It is a rare disease that affects 1 in 25,000 people globally. The prevalence of Diabetes Insipidus in percentage is 0.004% throughout the world. 

Diabetes insipidus is a disorder where the body does not retain water due to an insufficient supply of vasopressin. This results in heavy urination and intense thirst. 

Diabetes Insipidus is also known as “Water Diabetes” or “Arginine Vasopressin Deficiency.”


Diabetes Insipidus Pathophysiology

If you want to know the Diabetes Insipidus problem, you will have to understand the normal physiology and function of the hypothalamus-pituitary-kidney axis

Your hypothalamus secretes releasing and inhibiting hormones to regulate the homeostasis of the body. The pituitary gland, located below the hypothalamus, which stores vital hormones.  

Your pituitary gland has two sections – the anterior part (front) and the posterior part (back). 

Whenever you have low water concentration in your body, this posterior pituitary gets stimulated by the hypothalamus. It secretes a crucial hormone that’s called “Vasopressin“. 


difference between diabetes mellitus and diabetes insipidus

This vasopressin goes to your kidney and binds to the V2 receptor (Vasopressin receptor). After binding on the V2 receptor, it stops water excretion from the kidney. 

Due to its antidiuretic effect, vasopressin is known as “Antidiuretic Hormone (ADH).”

Overall, ADH prevents excessive water loss and reabsorbs the maximum water into your body to maintain hydration (or blood volume). 

If you have diabetes insipidus condition, you will be unable to control water loss due to a lack of ADH hormone. 

Usually, the urine output is 2 litre per day. In Diabetes insipidus, your urine output increases by 10 to 15 litres per day

In this condition, your ADH does not work properly. This ADH cannot produce sufficient quantity or could be due to improper binding of vasopressin to V2 receptors in the kidney. 

This causes increased water excretion from your kidney, which dehydrates your body. 

difference between diabetes mellitus and diabetes insipidus

Diabetes Insipidus Causes and Symptoms

Diabetes insipidus has two main symptoms – polydipsia (extreme thirst) and Polyuria (heavy urination). 

You may also have dehydration due to excessive loss of water. 

As far as the concern of the root cause of Diabetes insipidus, the Diabetes insipidus problem can be happened by three main reasons – 

  • Central diabetes insipidus – If you get an injury, damage or illness in some part of your brain such as hypothalamus or pituitary gland. This could be a reason to stop the release of vasopressin hormone.  
  • Nephrogenic diabetes insipidus – If you have a problem in your kidney (such as chronic kidney disease, urinary tract infection, electrolytes imbalance etc.). In that case, vasopressin cannot bind to V2 (vasopressin) receptor. 
  • Gestational diabetes insipidus – Sometimes, you may have diabetes insipidus during pregnancy. When you have a pregnancy, your placenta secretes a Vasopressinase enzyme that destroys the mother’s ADH. 


Diabetes Mellitus 

Diabetes Mellitus is directly related to blood sugar levels. The inadequate control of blood glucose levels is called Diabetes mellitus. In this condition, your body will have hyperglycaemia (or high blood sugar). 


Diabetes mellitus causes and symptoms

Diabetes mellitus is basically a heterogeneous group of disorders. It means there is no direct or single cause of diabetes mellitus; it can be due to multiple factors. 

You may have diabetes mellitus due to 

  • A virus, e.g., enteroviruses  
  • Environmental factors such as physical inactivity, unhealthy eating, smoking, obesity, stress, etc.  
  • Genetic cause. For example, diabetes mellitus runs in your family (like a grandfather, father, siblings, etc.)


As far as the concern of symptoms of Diabetes mellitus, you may experience the following symptoms at the initial stage of diabetes mellitus – 

  • Tiredness 
  • Polyuria (excessive urination)
  • Polydipsia (Intense thirst)
  • Polyphagia (feeling extreme hunger)
  • Dehydration 
  • Glucosuria (glucose in the urine)
  • Weight loss
  • Electrolyte imbalance


Diabetes Mellitus Pathophysiology

When you eat food, it converts into glucose. After that, glucose reaches your blood circulation and has to enter cells. 

But your glucose needs a key so that the gate can be opened, and this key lets the blood glucose into your cells for energy

The name of the key is “Insulin.” The entire story of Diabetes mellitus is related to Insulin. 

If you don’t have enough Insulin, your blood sugar may go up. This indicates your pancreas is not secreting Insulin from beta cells

Despite the fact that you have enough Insulin in your blood, your blood sugar level can still be high. 

A high blood sugar level with enough Insulin indicates Insulin Resistance.

It means your pancreas is releasing Insulin, but your cells are not accepting Insulin. This is called Insulin Resistance

The leading cause of insulin resistance is the over-stimulation of Insulin-on-insulin receptors (Tyrosine Kinase) by high-concentration Insulin.

It generally happens when you eat food frequently, and then your pancreas needs to release Insulin again and again. 

The continuous supply of Insulin causes Insulin Resistance. 

You may have Diabetes due to Insulin deficiency, Insulin resistance or both. 

This pathophysiology classifies your diabetes mellitus into – Type 1 and Type 2 Diabetes mellitus.  


Difference between diabetes mellitus and diabetes insipidus

Clinical featuresDiabetes mellitusDiabetes Insipidus
Prevalence Common Rare
RelationHigh blood glucoseIncrease passage of urine
Type of disorder Pancreatic disorderHypothalamic disorder
Deficiency Insulin hormone ADH (Vasopressin) hormone
Causes Insulin resistance and Insulin deficiencyADH (or Vasopressin) deficiency  
Blood sugar levelUnusual spikes of blood sugar level

(High blood sugar)

No spikes of blood sugar level (Normal blood sugar level)
Sugar in urine Present Absent
Symptoms Tiredness, Increased urination, excessive eating, intense thirst, dehydration, and weight loss More severe urination, dehydration and intense thirst
Urine concentrationNormal Dilute
Ketone bodies Positive Negative
Broad types Type 1 and Type 2Central and nephrogenic
Condition in pregnancy Gestational Diabetes Mellitus Gestational Diabetes Insipidus


difference between diabetes mellitus and diabetes insipidus

What is the difference between type 1 and type 2 diabetes mellitus? 

You may have diabetes mellitus in two types. It could be type 1 or type 2 diabetes mellitus. Here, I have clearly explained the difference between type 1 and type 2 diabetes mellitus.  


Type 1 Diabetes Mellitus (T1DM) 

T1DM is generally happened at an early age, below 40 years old. 

You can see this type of Diabetes in children or young adults. That’s why it is also called Juvenile Onset Diabetes Mellitus

In Type 1 diabetes, your pancreas losses the potential to produce Insulin. Therefore, Insulin does not secrete in your blood because Insulin-producing cells (Beta cells) of the pancreas get damaged. 

This type of Diabetes is totally dependent on Insulin. You will require insulin injection from outside. This is an Insulin Dependent Diabetes Mellitus (IDDM).

If there is no insulin, glycogenesis won’t happen. It means that it stops the conversion of glucose to glycogen, which causes increased glucose in your blood. 

Obesity is not a concern with Type 1 diabetes; it can be seen in non-fatty or lean people. 

The cause of T1DM is uncertain. It might be due to genetic or environmental factors such as viruses. 

Most cases of type 1 diabetes have been seen in the person who is exposed to an autoimmune disease. 

For example, if someone gets exposed to a virus, the human body produces antibodies to protect from that virus. Sometimes, these antibodies destroy the pancreas’s beta cells while fighting the virus. 

Some T1DM may be idiopathic (or have an unknown cause) because beta cells are not found in such types of people.  


Type 2 Diabetes Mellitus (T2DM)

T2DM is generally happened in late middle age, over 40 years old. 

You can see this type of Diabetes in adults or older age. That’s why it is also called Adult-Onset Diabetes Mellitus

T2DM is a group of diseases characterized by high blood glucose and insulin levels. 

In this type of Diabetes, Insulin is present. Still, there is a problem with insulin secretion, desensitization of insulin receptors or both. 

Let me explain in a nutshell.

You may have T2DM for two reasons, either insulin deficiency or insulin resistance. It also occurs by both mechanisms. 

  • Insulin Deficiency – Insulin is not secreting from pancreatic beta cells. 
  • Insulin resistance – There is no problem with insulin secretion. Insulin is well secreted from beta cells, but your cells do not accept Insulin. It means your insulin receptors (tyrosine kinase receptors) get desensitized due to overstimulation by high-concentration Insulin. 


T2DM usually begins with insulin resistance. 

It is not dependent on Insulin because Insulin is present. Still, due to resistance, it is unable to bind to receptors. So, you don’t require insulin injections from outside. This type of Diabetes is a Non-Insulin Dependent Diabetes Mellitus (NIDM). 

T2DM is highly associated with obesity and can be seen in fatty or obese people. 

Multiple factors are involved in to cause of T2DM, such as older age, family history, obesity, physical inactivity, stress, lousy lifestyle etc. 

Sometimes T2DM can happen in young people. This is called MODY (Maturity Onset Diabetes Mellitus)

MODY usually happens due to a mutation in the glucokinase gene. 

Glucokinase is an enzyme that helps in the conversion of glucose to glucose-6-phosphate in the Glycolysis cycle

In MODY, this metabolism gets impaired due to a lack of glucokinase enzyme. 

Difference between Type 1 and Type 2 Diabetes Mellitus

Clinical features Type 1 Diabetes MellitusType 2 Diabetes Mellitus
Prevalence Less prevalent (Rare)More prevalent (common)
Onset SuddenGradual
Age at OnsetChildren or young adultAdult or Older
Body habitus Lean peopleFatty people
Also known as Juvenile Onset Diabetes MellitusAdult-Onset Diabetes Mellitus
Insulin dependency DependentNon-Dependent
Pathogenesis Insufficient InsulinInsulin resistance, insulin insufficient or both
Causes Autoimmune disease, genetic disease (mutation in HLA gene)Virus, family history, environmental factors such as obesity, stress, physical inactivity, bad lifestyle, etc. 


What can be the similarities between diabetes mellitus and diabetes insipidus? 

Diabetes Mellitus and Diabetes Insipidus have a very obvious similarity starting with the first letter.

Even though both diseases are entirely different; still, these diseases may increase thirst, craving for more fluid intake, dehydration, and heavy urination. 

These symptoms can be seen in both diabetes conditions. 



I think that I would have cleared all your doubts about diabetes mellitus and insipidus. 

Now, you got to know what difference between diabetes mellitus and diabetes insipidus

They are not similar diseases, but these diseases share their only first name and some symptoms. 

Diabetes mellitus is associated with high blood sugar levels and increased urination. In contrast, diabetes insipidus is only related to heavy urination. 

This is only an informative article. If you find any problem related to Diabetes, whether it is mellitus or insipidus, you must consult your doctor. 

Please share this post with your friends, relatives and family members so that they learn about these diseases. 

Have any questions?

Ask in a comment box. 



Q 1. Why are diabetes mellitus and insipidus called Diabetes?

Diabetes means passing excessive amounts of urine. This symptom is very common in both conditions, diabetes mellitus and insipidus. That’s why they share the first name “Diabetes.” 

Q 2. What is diabetes insipidus also known as?

Diabetes Insipidus is also known as “Arginine Vasopressin Deficiency.” Or “Arginine Vasopressin Resistance”. 

Q 3. What is the hallmark of Diabetes insipidus?

Polyuria (heavy urination) is a hallmark sign of Diabetes Insipidus. 

Q 4. Can you have both diabetes mellitus and diabetes insipidus?

It rarely happens who develop concurrent diabetes mellitus and insipidus together. As per a study, some cases got Diabetes mellitus and insipidus together. 

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