Diabetes Insipidus and Diabetes Mellitus

The word Diabetes is well known and it is mostly associated with a disease involving difficulties with sugar. There are actually two unrelated diseases named Diabetes - Diabetes Mellitus and Diabetes Insipidus. This article is to highlight each and to show the differences between the two.

Diabetes Mellitus and Diabetes Insipidus in  a nutshell #DiabetesMellitus #DiabetesInsipidus



Both diseases are dependent on the action of hormones; Insulin for Diabetes Mellitus and Vasopressin for Diabetes Insipidus.  Insulin is produced in the pancreas. Vasopressin is produced by the Hypothalamus and stored in the pituitary gland. Insulin is necessary for the utilization of sugar/glucose. Vasopressin is the hormone that regulates the body’s retention of water.

In both the diseases there are variances derived the same way. A lack of or not enough of the hormone and a specific type of the disease is present. A lack of Insulin and the disease is Diabetes Mellitus Type 1. A lack of Vasopressin and the disease is Neurogenic Diabetes Insipidus.

When the body is unable to use the hormone effectively another condition is present. Diabetes Mellitus Type 2, when the cells are insulin resistant.  When the kidneys are insensitive to vasopressin, Nephrogenic Diabetes Insipidus (vasopressin-resistant) is the result.

During pregnancy, the body is subjected to a multitude of diverse hormones and chemical reactions, caused mostly by the placenta. This hormonal imbalance can cause a temporary disease that occurs only during the pregnancy. The resistance to Insulin results in gestational diabetes mellitus. A deficiency of vasopressin causes gestagenic diabetes insipidus, also known as gestational diabetes insipidus. With both diseases, the body returns to normal shortly (four to six weeks) after the delivery.

Diabetes Insipidus have a fourth condition, with no equivalent in diabetes mellitus. Dipsogenic Diabetes Insipidus is caused by abnormal thirst and therefore the excessive intake of water and/or other liquids. The body’s reaction to diabetes mellitus can also lead to abnormal thirst, but it is merely a symptom of diabetes mellitus and not a separate sub-classification thereof.

Both diseases share the same symptoms of increased urination and thirst. In diabetes insipidus, these symptoms are much more pronounced.


The most common diabetes is mellitus, insipidus is more rare and unknown. Take for example the terminologies used by both. Terms that are more familiar are insulin, pancreas, type 1, type 2 and gestational. They are all familiar terms, related to diabetes mellitus. If diabetes insipidus were the more prevalent disease, then unfamiliar terms such as vasopressin, hypothalamus, pituitary gland, gestagenic and antidiuretic would be more familiar to the average vocabulary.

Diabetes mellitus is also known as “sugar diabetes” and diabetes insipidus as “water diabetes”

Vasopressin controls the reabsorption of molecules in the kidneys by affecting the tissue's permeability. When there is enough vasopressin present, the water, after purification by the kidneys are re-absorbed into the tissues. If the water is not re-absorbed then it will pass through to the urinary tract and expelled from the body. When dehydration occurs, vasopressin is released and water is retained in the body.

Insulin is compatible with the cells receptors, glucose (simple sugar) is not. In order for the glucose to enter the cells, the compatibility of insulin with the cell’s receptors must be utilized. Without insulin, the much needed, energy-laden glucose is unable to enter the energy-starved cells.

In diabetes mellitus, the excessive urine is caused by the kidneys expelling the copious amounts of sugar in the blood and needing lots of water to dilute the sugar- laden urine.  In answer to the high levels of glucose in the blood, the kidneys flushing out the extra glucose in urine, drawing extra water from the body to dilute the glucose.

The excessive urine in diabetes insipidus is caused by the lack of and/or the inefficiency of vasopressin.


Diabetes comes for the Greek word “Diabainein”, literary meaning siphon, passing through, to stride or stand with legs apart. From dia- “through” and bainein- “to go”. The word refers to the excessive amount of urine of the diabetic.  In the distant past, diabetes was also known as “the pissing evil”.

Mellitus literally means "sweet urine". In the past, the doctors tasted the urine to help them in the diagnosis of diabetes mellitus.

Insipidus literally means bland, without taste. The urine is extremely diluted and a very pale yellow, almost clear.


Diabetes mellitus and diabetes insipidus are two unrelated diseases that only share a name and some symptoms. The two must not be confused.

Learn more about of these two diseases.

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