Difference between Diabetes Mellitus and Diabetes Insipidus

Diabetes Mellitus and Diabetes Insipidus

Although they share the same first name and some of the symptoms diabetes insipidus and diabetes mellitus are completely different diseases. They cause different problems and they have different treatments. In this topic, we will explain a bit about both of the diseases and then move on to what the primary differences between them are. 

Diabetes Mellitus

Diabetes mellitus is general diabetes that most of the population suffer from. It involves several conditions on how your body turns food into energy. When you eat carbohydrates, your body turns the food into a sugar called glucose and the hormone insulin regulates the flow of glucose in your bloodstream. If there is a low level of insulin secretion in your body, then your blood glucose levels will increase which leads to a condition called high blood sugar. It can cause serious health problems and if not controlled can be life-threatening. It comes in different forms

  • Prediabetes: It is a condition when your blood glucose levels are higher than usual but not so high that it can be diagnosed as diabetes

  • Type I Diabetes: This is also called insulin-dependent diabetes and is an auto-immune condition where your body attacks your pancreas with antibodies. Thus the pancreas is damaged which results in low levels of insulin secretion and high levels of blood glucose. This condition can damage the blood vessels of eyes and kidneys. The treatment involves injecting insulin into the fatty tissue under the skin with the help of syringes and insulin pens.

  • Type II Diabetes: It is also referred to as non-insulin-dependent diabetes. It is observed mostly in people suffering from obesity. In this condition, the patient’s body produces insulin but it is not enough to control blood glucose levels. It causes the same health complications as type 1 diabetes. The only way to keep this type of diabetes in control is to lead a healthy life; eating right, exercising and keeping a healthy weight.

  • Gestational Diabetes: Pregnancy can cause insulin resistance. If this leads to diabetes then doctor’s call it gestational diabetes. It is usually spotted in middle or late pregnancy. Gestational diabetes should be controlled as it poses a risk for the foetus. The new-born baby might gain weight after birth and face trouble breathing. The treatment includes meal planning for the mother, daily exercise, taking insulin and keeping weight under control.

Diabetes Insipidus

Diabetes insipidus is a condition where your kidney produces abnormally large volumes of dilute and odourless urine. The kidneys of an affected patient can pass up to 20 litres of urine. As a result, the patient would have to drink large amounts of fluid. There are four types of diabetes insipidus:

  • Central: The reason behind central diabetes insipidus is damage to a person’s hypothalamus or the pituitary gland which results in abnormal production storage and release of vasopressin. The issue causes the kidneys to remove excess fluid from the body.

  • Nephrogenic: The causes of this type of diabetes insipidus are gene mutation or inherited gene changes which lead to the kidneys not functioning normally. Some of the symptoms are low potassium and high calcium levels in the blood.

  • Dipsogenic: A defect in the thirst mechanism located in the brain's hypothalamus causes this type of diabetes insipidus which increases the thirst and the liquid intake of a person. It also suppresses vasopressin and increases the passing of urine.

  • Gestational: This happens during pregnancy.


The general symptoms of diabetes insipidus are:

  • Thirst

  • Nausea

  • Dry skin

  • Fatigue

  • Dizziness etc.

The treatments for diabetes mellitus include hormonal therapy, medication to balance mineral levels in the body and living a healthy life.

Differences Between Diabetes Mellitus and Insipidus

Each disease has its own set of specific characteristics. The following table lists those differences.

Diabetes Insipidus vs Diabetes Mellitus

Diabetes insipidus 

Diabetes mellitus

It is caused due to defects in the brain’s hypothalamus. 

It is caused due to defects in the pancreas.


Another reason is the deficiency of ADH.

The major reason is the deficiency of the insulin hormone.

Blood glucose levels do not increase and there is no presence of glucose in urine. 

Blood glucose levels increase and it is present in urine.

The urine is diluted and odourless.

There is no change in the concentration of urine. 

The disorder causes excessive urination. 

Urination is lesser than diabetes insipidus.

There is no increase in blood cholesterol. 

Blood cholesterol increases.

There are no changes in eating patterns.

Excessive hunger is seen in patients.

Ketone bodies are not present in the urine

Ketone bodies are present in urine.

The incidence rate is 3 in 100,000.

The incidence rate is 770 in 100,000

The symptoms include excessive urination and thirst with headaches.

The symptoms are high blood sugar, increased thirst and hunger etc.


FAQ (Frequently Asked Questions)

1. How is diabetes mellitus diagnosed?

There are several ways diabetes mellitus can be diagnoses

  • Urine analysis: Patients with diabetes mellitus will have increased glucose levels in urine. However multiple tests should be done for accurate results.

  • Blood tests: fasting blood glucose test, haemoglobin A1C test, oral glucose tolerance tests are some of the ideal tests for confirmation of diabetes mellitus.

  • Screening: Screening is done for patients affected with type II diabetes who show no symptoms. It is recommended for children who are obese and also overweight adults.

2. What type of hormone treatment is used for diabetes insipidus?

A man-made hormone called desmopressin is used to treat diabetes insipidus. It replaces the missing ADH hormone and decreases urination.  The hormone works by increasing water permeability in renal tubular cells and decreases urine volume and increases urine concentration.

3. What are the three major signs of diabetes mellitus?

The three major signs of diabetes mellitus are:

  1. Polydipsia: This corresponds to increased thirst.

  2. Polyuria: Increase in urination

  3. Polyphagia:  Increase in appetite leading to binge eating.

These are also known as the three P’s and they often but not always occur together.


4. How is diabetes insipidus diagnosed?

A common test is ‘water deprivation. It takes several hours and the patient is not allowed to drink any fluid on the day of the test. Initial blood and urine tests are carried out to measure the salt levels and the concentration in both. 


At hourly intervals, the tests are repeated along with checking blood pressure, weight and the amount of urine passed.


If the blood sodium or concentration levels rise above the normal range along with low urine concentration, then it is likely that the patient has been diagnosed with diabetes insipidus.