Diabetes Insipidus – time to change the name?
Article by Prof John Newell-Price
Diabetes insipidus literally means passing lots of insipid or ‘tasteless’ urine. In the general population it is very uncommon, but plenty of patients with pituitary disease have diabetes insipidus. The term ‘insipid’ was originally used long before modern medicine to make a distinction between diabetes ‘mellitus’, or ‘sugar’ diabetes, where the urine is sweet due to the high sugar content.
It is of course only too self-evident from almost daily press coverage that diabetes mellitus is very common, with the numbers of people affected worldwide and in the UK increasing year on year. ‘Insipidus’ and ‘mellitus’ are time-honoured names that were originally coined before any real understanding of the underlying causes. The word ‘diabetes’ is derived from the Greek word that means ‘syphon’ or ‘go through’, referring to the production of lots of urine, that occurs in both diabetes mellitus and insipidus, when uncontrolled.
The cause of the large volume of urine in the two conditions is completely different. In diabetes mellitus the high sugar levels are filtered in the kidney and this draws more water with it, forming a higher volume of sugary urine. By controlling the blood sugar, the volume of urine reduces, and the reduced sugar levels have wide-ranging benefit throughout the body. In diabetes insipidus due to pituitary problems, there is a lack of the hormone vasopressin (also called anti-diuretic hormone, or ‘ADH’) from the posterior pituitary, and this is termed ‘Cranial (in the head) diabetes insipidus’. Without vasopressin, the kidney cannot concentrate urine and so lots of dilute urine is passed. Treatment is with desmopressin, a synthetic long-acting form of vasopressin. There is a less common form where instead of there not being any vasopressin, the kidney does not respond to vasopressin, termed ‘Nephrogenic (in the kidney) diabetes insipidus’.
One major problem for patients with diabetes insipidus is the word ‘diabetes’. The general population, the press, and many health care workers have knowledge only of diabetes mellitus. This is understandable given the huge prevalence of the condition, but it is exactly this lack of knowledge that puts patients with diabetes insipidus at risk.
There have been highly publicised tragic cases of patients with diabetes insipidus being denied access to desmopressin when admitted to hospital and dying as a consequence. In these terrible cases the problem was the lack of recognition that ‘diabetes insipidus’ was not ‘diabetes mellitus’, with the word ‘diabetes’ causing the problem. Patients with diabetes insipidus experience many other and varied difficulties but the word ‘diabetes’ is not helpful to them. Some patients have both conditions.
It is for these reasons that there has been a move to see whether the name of diabetes insipidus could and should be changed. This initiative has been led by Dr Malcolm Prentice, who has written a commentary in the journal ‘Clinical Endocrinology’ that is free to download here.
In this short article he calls for the name ‘Cranial Diabetes Insipidus’ to be changed to ‘Pituitary insipidus’, so that it is clearly different from diabetes mellitus, and so to improve safety for patients. Changing names in medical terminology is possible, but takes much time and agreement. The societies of endocrinology, and other professional and learned bodies from several countries are discussing this, and whilst there is no guarantee that the name will be changed it is a starting point that will hopefully lead to better care.
(For more details of diabetes insipidus please see The Pituitary Foundation booklet ‘Diabetes Insipidus’)