Tuesday, 13 August 2013

Diabetes is usually the result of a visit to the doctor

Patient mongering is the process by which the medical profession creates new patients out of people who have considered themselves to be normal. There are many examples of this and one is diabetes, of which there is alleged to be an epidemic.

 It could be argued that the commonest cause of diabetes is going to see the doctor. Any of us might be summoned for a "routine check". We go in perfectly well but we come out with diabetes. In fact it has been part of UK government policy to encourage diabetes case-finding by family doctors. By WHO standards the diagnosis of diabetes has been based on the finding of a blood sugar concentration of 11 mmol/L on at least two occasions. However the goalposts have been widened and a blood glucose above 8 has now appears to have become the threshold for diagnosis. We can take things a stage further and people (now patients) are told that they have diabetes even without any measurement of blood glucose.

For many years in the control of diabetes, especially brittle type 1 insulin dependent diabetes, it has been realised that a blood glucose recording is only a snapshot and not a very good basis for adjusting treatment. The came along a new test, HbA1C, a measure of glucose attached to haemoglobin. This was found to be a better measure of diabetes control, reflecting glucose control over a long period of time.

When a well person attends the family doctor (more likely the practice nurse) for the "routine check" a series of blood tests will be ticked off on the request form and HbA1C is now likely to be included. If it is marginally elevated then the person will become a patient with diabetes, and probably an unhappy patient who continues to feel perfectly well.

It is little surprise that we have a declared epidemic of diabetes. Is it an epidemic of disease or an epidemic of diagnosis with a lower threshold? It certainly has an effect on the person diagnosed. There will be inevitably anxiety with concerns about future blindness or legs amputated, consequences that in reality we do not see today. The financial consequence is an increase in insurance premiums, and possibly detrimental effects on employment.

Does the diagnosis of diabetes benefit the person in any way? A community based study of 15,000 people in the east of England received the award from the British Medical Association this year for its investigation of this. [1] The study involved enthusiastic case-finding of diabetes in certain general practices but not in the others. The health outcomes of the two groups turned out to be identical after 10 years, no difference in total deaths, heart deaths, cancer deaths etc. Case finding was clearly shown to be of no benefit. However negative results of this sort do not deter enthusiasts, especially when there is financial reward to the doctors and other health professionals, and also of course the pharmaceutical industry.

The disadvantage of type 2 diabetes has been the cardiovascular associations, mainly coronary heart disease (CHD). In fact it has often been following a heart attack (myocardial infarction, MI) that type 2 diabetes has been identified. More recently it has been by case-finding described above. Now that the epidemic of CHD is virtually over (see previous post, An epidemic of CHD) the disadvantage of type 2 diabetes is also diminishing. The prognosis for people with type 2 diabetes is now little different from the general population.

An interesting Viewpoint on type 2 diabetes appeared in the Lancet recently, written by Edwin Gale, professor emeritus at Bristol University, UK [2]. Although in some respects a bit heavy and philosophical, it is also like a breath of fresh air. Gale points out that in 1907 it was said that diabetes could only be defined in terms of glucose, and that this view has never been successfully challenged. He argues that if after more than a century type 2 diabetes can still only be defined as "idiopathic hyperglycaemia" (high blood glucose of unknown cause) then let us call it that. The term diabetes implies a specific disease process but type 2 diabetes isn't. "Diabetes" itself is a translation of "plentiful urine" of which there are two types: "mellitus" means sweet or honey-like, containing sugar, and other much more rare type is "insipidus", meaning insipid or tasteless. Such a descriptive term for type 2 diabetes is inappropriate in the present era. Now that we are in the era of case-finding by blood testing, we rarely find glucose in the urine, and no excess of urine production.

In the absence of coronary heart disease the disadvantage of a high blood glucose is not clear and the Cambridge study above suggests that there is no disadvantage. Gale has a long interest in the epidemiology of diabetes and he emphasises the continuum of blood glucose levels in the population. Demarcation between normal and diabetes is artificial. He goes on to indicate that the level that determines whether or not a person has "diabetes" is decided by a committee rather than by a function of nature, and so as mentioned above the prevalence of the condition can be changed overnight, thereby creating a pseudo-epidemic and robbing many people of their perception of good health. Doctors are very good at this.

References:

1. Simmons RK et al. Screening for type 2 diabetes and population mortality over 10 years (ADDITION-Cambridge): a cluster-randomised controlled trial.  Lancet 2012; 380: 1741-48.

2. Gale EAM. Viewpoint: is type 2 diabetes a category error? Lancet 2013; 381: 1956-57.



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