Fat, Fate, and Disease : Why we are losing the war against obesity and chronic disease (9 page)

The diseases we are concerned with in this book, particularly diabetes and cardiovascular disease, often creep up on us. We are concerned with the emergence of type 2 diabetes, which is generally much more insidious, unlike that of insulin-dependent (type 1) diabetes, which usually starts with an acute episode—sometimes even loss of consciousness. Many people have it without knowing, and it is only when they have their blood sugar levels checked that they find that they suffer from this disease. Similarly, while some people discover they have cardiovascular disease when they have a heart attack or a stroke, a thorough medical examination would usually have uncovered high blood pressure or altered blood lipid levels well before these more serious events occurred. A very high proportion of people have such signs but know nothing about it. One of the problems of this subtle appearance of disease is how to define when disease is present.

Not only can individuals be unaware of these health problems but so too can public health organizations. Just recently, in 2010, the estimate of the number of people with diabetes in China had to be revised upward dramatically. As more information became available it was found that the previous estimate of 45 million was far too low. Indeed official figures suggest that there are now about 100 million people in China with diabetes and this may still be an underestimate. Getting accurate figures is impossible unless extensive population studies are undertaken.

Thousands of pages in medical journals have been filled with debate and discussion about how best to define diseases such as diabetes or hypertension. The problem is that there is not a sharp dividing line between normal and abnormal—and what is healthy for one individual may be unhealthy for another. It is easy to say whether or not a person has a broken leg, or whether or not your child has measles. It is much more difficult when ill health which may have had its roots in childhood (or even before) emerges over many years.

The question is made more complex because what may start as very subtle changes such as thickening of the walls of our blood vessels, which we know can even be present in quite young children, does not emerge as high blood pressure or heart disease until decades later. And how rapidly these clinical conditions emerge may be influenced by many things, such as how much we exercise, what we eat, how stressful our jobs or our personal lives are, and, as we shall see in later chapters, by other biological factors such as our genetic and epigenetic make-up.

So when does a person move from being healthy to being unhealthy? We could say that they are unhealthy as soon as their physiology indicates a deviation from normal, even if they do not show any signs of disease. On the other hand we could wait until the person’s productivity and quality of life are affected—perhaps following a heart attack or angina or a stroke—but isn’t that shutting
the stable door after the horse has bolted? So the answer must lie somewhere in between, when some threshold of abnormality is reached—say in blood levels of the markers of inflammatory processes which are part of the disease process. In practice this is the sort of definition that is generally used—but only after a lengthy academic discourse allows a consensus to be reached on what is normal and what is not in terms of the choice of such markers and their levels.

While we need to have some working definitions, there is a flawed set of concepts underlying the problem. We are dealing with a broad and continuous range of possible measurements. Consider adult height in men—obviously it varies considerably. Furthermore the average height of a man from Holland is different from the average height of an Inuit man from Northern Canada. One is tall and thin, the other short and stocky. Not only is the average height different but so is the range of heights observed. We can imagine that there will be more extremely tall men in Holland than on Baffin Island, and that in absolute centimetres we would find a greater percentage of men under the height of 160 cm on Baffin Island than in Amsterdam. And if we compared them with men from the Efe, a pygmy tribe from the Congo, a short Inuit man might be considered a tall by the Efe man.

So what constitutes an abnormally short male? We can see that no definition based simply on height makes sense. It clearly depends on ancestral background—whether a man is an Inuit, a Dutchman, or an Efe. It also depends on his parents—short parents tend to have short children and tall parents tall children, because genetic influences are involved. So we might expect that if a very short Dutch man married a very short Dutch woman, their offspring will be at the short end of the height range. So does this make the short Dutch man abnormal? Statistically he may be right at the lower end of the range of heights seen in Holland: 99 per cent of the male population may be taller, but this still does not make him ‘abnormal’. After all, somebody has to be at the extreme end of the normal range—just as
someone has to be the oldest person in the world on any one day. But it is also possible that he does have a biological problem which is affecting his growth. There are genetically transmitted forms of short stature—achondroplasia is one example—so perhaps the Dutch man’s family has heritable achondroplasia. Achondroplastics are easy to recognize—they are very short people with relatively large trunks and heads and very short arms and legs. But there are also much more subtle genetic defects that lead to short stature without obvious skeletal abnormality.

So when we talk about the ‘normal range’ for height, it is a purely statistical definition taken from measuring lots of people—it says nothing about whether people outside this range are abnormal. To determine this we have to do more tests or examine them in some other way.

Equally, a person may have a height well within the normal range but still be abnormal. The individual may be a respectable 175 cm tall but have had very tall parents. When we examine him or her carefully we may find that he or she has coeliac disease which impairs digestion. The individual has had his or her growth affected and has not grown to full genetic potential. Yet from a purely statistical measure of height he or she appears normal.

The point we are making is that whenever we have a continuous measure—that is one which does not break down into discrete compartments like fractured or intact, male or female—then definitions become statistical. We can be fairly certain whether or not an individual has a broken leg without needing to compare him or her to others. But just knowing someone’s height tells us little about their normality or health without a lot more information. It gets very complex when we start looking at the pathways to diabetes and cardiovascular disease.

We believe that it is not the presence or absence of an abnormal finding that defines the risk of diabetes and cardiovascular disease; rather it is the pattern of the life-course of the individual, and his or
her particular context, that puts him or her at greater risk. This is a new concept, and one of great importance, but it also sits uneasily with doctors who are more used to traditional diagnostic approaches. A patient complains of pain in the chest. Is it indigestion—yes or no? Is it a heart attack—yes or no?

Diabetes and cardiovascular disease have long been recognized as problems of the developed world. For many years they were seen to be diseases of affluence because they appeared to be predominant in richer countries. But within these countries it is actually the poorer, more disadvantaged people who are now more at risk. There are many reasons why this is the case—cheaper foods tend to be less healthy, socio-economically disadvantaged people face barriers in accessing healthcare rapidly, and they are more likely to smoke.

They are also more likely to have jobs in which their autonomy is limited. Recent studies by Sir Michael Marmot of public servants in the UK and population groups in eastern Europe show that ill health is more likely in people with less control over their lives. So people who worked in jobs where they simply had to do what they were told, with little opportunity to show initiative or flexibility, were more likely to have heart disease and other chronic illnesses. In Marmot’s study lower-ranking civil servants in the UK were more at risk than higher-ranking colleagues. As we shall see in later chapters, this does not just apply to the UK, because poorer, less educated people in many countries live in cycles of disadvantage which affect their health in successive generations.

In a typical Western country about half of us can expect to die of cardiovascular disease. But we will do so at an advanced age, unless we are unlucky or poor, because our healthcare services can provide drugs, surgery, stents to keep blocked arteries open, and even heart transplants. Of course this effort consumes large sums of money—between
5 and 15 per cent of an advanced country’s GDP goes into providing health services late in an individual’s life. Our societies value this investment as a social good because we now live much healthier, productive, and enjoyable lives well into our post-retirement years. It is also an economic good because over the past two decades improvements in healthcare and public health measures such as reducing smoking have delayed the appearance of cardiovascular disease until much later in life. This in turn has led many Western governments to consider raising the statutory age of retirement—which is helpful for them in tough economic times.

But there is a growing concern that, with the rising epidemic of abdominal obesity, the gains may be reversed. Could it be that we will again start seeing heart disease at an earlier age? There are respected researchers who argue that this is indeed the case. If they are right we may see life expectancy, which has risen progressively across developed nations, start to decline again. Children born today may not live as long as their parents.

One frightening hint comes from studies of diabetes in Western countries. Type 2 diabetes used to be called ‘maturity onset diabetes’ because 40 years ago it generally appeared in the sixth or seventh decade of life. Seeing an adolescent who had type 2 diabetes was very rare. But now in a typical paediatric diabetic clinic almost half of new patients will have type 2 diabetes—the term ‘maturity onset’ is no longer meaningful.

The longer a person has type 2 diabetes, the more likely the nasty complications of heart problems, blindness, and kidney disease are to occur. Even with good diabetic control—and that is not as easy as it sounds—complications will appear if the person lives long enough. So if the disease starts four decades earlier than it used to, we can anticipate more complications in the later, but still potentially productive, years of our lives. We are worried by this trend, and so are paediatricians and doctors throughout the Western world.

We are used to thinking of the diseases of the developing world as being associated with under-nutrition and infection. And sadly, it is true that almost a billion people around the world still struggle to have sufficient food and adequate nutrition. Too many children in Africa, Asia, and Latin America grow up stunted, a sign of chronic under-nutrition and ill health. Malaria, tuberculosis, polio, bilharzia, and many other tropical infections still affect millions of people, with potentially horrific consequences. Even the most basic aspects of public health and medical care are absent for many people. Clean water is unheard of in some places. Nearly half a million women die each year in pregnancy or childbirth, reflecting the lack of the most basic obstetric and midwifery services, and each year some 8 million children die before their fifth birthday—largely in Africa and southern Asia.

This is the classic picture we all have of the pattern of disease in developing countries. But that picture is incomplete. For in the last two decades we have seen the start of a new epidemic in these countries: of diabetes and cardiovascular disease and other complications of obesity. Indeed it is now estimated that almost as many people in the developing world suffer from these chronic diseases—which many of us think of as resulting from excess—as from under-nutrition. And cancer, allergic disease, and senile dementia are also rising rapidly in developing countries. Up to 20 times as many people globally die from non-communicable disease as from HIV. But what is frightening is that the rate of diabetes and cardiovascular disease is rising rapidly. The predictions of future incidence, while astronomical, are in our view likely to be underestimates.

Some hospitals in Beijing report rates of diabetes in pregnancy of more than 20 per cent. Indeed across Asia the rate of diabetes in pregnancy has risen dramatically. As diabetes in pregnancy is an early warning of diabetes exploding in a population, we think that,
unchecked, the rate of diabetes in China will rise dramatically in the next two decades from its already alarming level. The same is true of India. Even in Africa, the continent of under-nutrition, rates of diabetes and heart disease are rising, particularly in populations migrating from the countryside to cities such as Lagos. Some of the highest rates of diabetes are on small island states such as Nauru, where more than 40 per cent of the adult population can be affected.

As in developed countries, diabetes and cardiovascular heart disease are appearing in people in developing countries at relatively young ages. For example, in India more than 60 per cent of newly diagnosed diabetics are under the age of 50, and 25 per cent are in their thirties. Such an early onset will impact on the quality of life of entire families as well as putting impossible burdens on rudimentary health systems and impeding economic development. The implications of all of this for trying to close the so-called North–South divide—a symbol of the health inequalities across the globe—are extremely worrying. This is why the British Commonwealth nations at their 2009 meeting of heads of state in Trinidad and Tobago urged action to be taken. In response to this, Ban Ki-moon, the United Nations Secretary General, called a special General Assembly Summit in 2011 to address the issues of non-communicable disease in the developing world. And that is one of the reasons we have written this book.