difference between diabetes mellitus and insipidus
Metabolic Health

Diabetes Mellitus Vs Diabetes Insipidus

Although Diabetes mellitus and diabetes insipidus share their first name, they are different conditions. The difference between Diabetes mellitus and diabetes insipidus ranges from their causes and diagnosis to treatment.

What is Diabetes Mellitus?

Distinguished by excessive blood sugar levels, Diabetes mellitus is caused by the inability of our body to produce sufficient insulin (controls the blood glucose levels) or the failure of our body to use the insulin.

What is Diabetes Insipidus?

Diabetes insipidus is caused by insufficient antidiuretic hormone (ADH) in your body. Therefore, the kidneys produce a large amount of dilute and odourless urine, causing an imbalance of fluids. The causes of Diabetes insipidus vary with its following types:

  • Central: It is caused by hampered secretion of ADH from the brain, primarily due to damage in the hypothalamus or pituitary gland area.
  • Nephrogenic: Mostly attributed to genetic causes, nephrogenic Diabetes insipidus is allied with a hampered response of the kidneys to the ADH because of which they cannot retain water properly.
  • Dipsogenic Diabetes insipidus: Sometimes associated with mental conditions, dipsogenic Diabetes insipidus is caused by drinking too many fluids (excessive thirst) due to affected thirst regulating mechanisms in the hypothalamus.
  • Gestational Diabetes insipidus: Occurs during pregnancy.

Other Diabetes insipidus causes are:

  • Head injury
  • Surgery
  • Brain tumour

Difference Between Diabetes Mellitus and Diabetes Insipidus

Diabetes Mellitus Diabetes Insipidus
Deficiency Insulin ADH
Blood sugar level High Normal
Type of disorder Pancreatic Hypothalamic
Ketone formation Occurs Does not occur
Urine Volume Excessive Enormous
Cholesterol level in the blood Increases Normal
Urine concentration Normal Very dilute
Excretion of sugar in the urine Yes No

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Symptoms of Diabetes Mellitus and Diabetes Insipidus

Although the symptoms of both these conditions are somewhat similar, the difference between Diabetes mellitus and Diabetes insipidus lies in their causes. Some common symptoms are:

1. Thirst: Diabetes insipidus is classically characterised by excessive thirst, as a large amount of fluids leave your body, making you constantly feel thirsty. However, in Diabetes mellitus, excess thirst can be attributed to increased blood glucose. Your body demands more water to help flush the excess blood sugar.

2. Exhaustion: In diabetes insipidus, the excess loss of fluids from the body causes dehydration making you feel exhausted. The feeling of exhaustion is mainly because of the lack of electrolytes (potassium or calcium) that get flushed out of your body via urine. Whereas in Diabetes, you may feel exhausted because of fluctuation of blood glucose levels between too high or too low.

3. Blurred vision: In Diabetes insipidus, you may experience blurred vision when you stay dehydrated for a long time. In comparison, Diabetes mellitus is associated with blurred vision because of the excess sugar in the blood, which affects your eyes and vision in several ways.

Besides, Diabetes insipidus symptoms also include polyphagia (excessive hunger) and polyurea (frequent and excess urination). While Diabetes mellitus symptoms also comprise delayed healing of wounds, recurring infections, and numbness in hands or legs.

Diagnosis of Diabetes Mellitus and Diabetes Insipidus

Diabetes mellitus can be diagnosed by a few blood tests, including a fasting blood test, wherein your blood is drawn after you haven’t consumed anything for at least eight hours. The other is the HbA1c, or glycated haemoglobin test, which doesn’t require fasting.

On the other hand, doctors have several ways to diagnose Diabetes insipidus.

1. Blood test: The blood test for Diabetes insipidus measures your sodium levels.

2. Urinalysis: This test evaluates if the urine is dilute (watery) or concentrated and the amount of urine your body produces in twenty-four hours.

3. Fluid deprivation test: The fluid deprivation test gauges the amount of urine your body produces when you are not drinking any fluids. There are two types of this test; a short one which can be taken at home, and a longer one, often conducted in the hospital, where they measure your other parameters as well.

4. Magnetic resonance imaging (MRI): MRI can help detect any problems with your hypothalamus or pituitary gland (caused by a gene mutation, infection, tumour, or surgery) which can cause this disease.

Treatment of Diabetes Mellitus and Diabetes Insipidus

There is no 100% cure for both Diabetes mellitus and Diabetes insipidus. However, by changing your lifestyle and taking specific measures, you can manage them quite well.

Diabetes mellitus treatment comprises a combination of medications like insulin combined with some lifestyle changes. The lifestyle changes include regular exercise or walking, eating smaller portions of healthy meals frequently, and reducing your sugar intake. You can manage Diabetes mellitus by regularly checking your weight, blood pressure, and cholesterol levels and monitoring your blood glucose levels.

Diabetes insipidus treatment is based on which type of Diabetes insipidus you have from the mentioned ones.

1. Central: A synthetic hormone that mimics ADH (called desmopressin) can replenish vasopressin deficiency. It is available in the form of a nasal spray, pill, or shot.

2. Nephrogenic: Treatment of this type is slightly tricky and needs the right combination of drugs. A combination of medications like water pills, ibuprofen or aspirin can help you cure or minimise symptoms of Diabetes insipidus.

3. Dipsogenic: Treatments for this type are not that effective. However, addressing underlying conditions like mental illness may help alleviate the symptoms.

4. Gestational: As this type of Diabetes insipidus is restricted to pregnancy, most women don’t need treatment after giving birth. Usually, desmopressin is used to treat this condition.


Diabetes mellitus is associated with increased blood glucose levels, while Diabetes insipidus is caused by a deficiency of a hormone called vasopressin which leads to excess and frequent urination, causing an imbalance of body fluid. These conditions share some similar symptoms like exhaustion, excess thirst and blurred vision. Although there is no complete cure for them, both conditions can be well managed with the help of appropriate medications.  


1. Can you have both Diabetes mellitus and Diabetes insipidus?

Yes, but in very rare circumstances. As such, both conditions are unrelated, and as research suggests, very few cases, just about fifty cases, have been noted. The simultaneous occurrence of these two conditions is highly fortuitous except in rare genetic conditions or pituitary tumours that cause the onset of both Diabetes mellitus and Diabetes insipidus.

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