One reason why the mainstream has not given up the classical theory is that a stronger and more convincing alternative theory is not yet agreed upon. The Diabetes Code tries to do this, but alas, with an almost equally weak case.
Book Review of:
Fung, Jason (2018). The Diabetes Code: prevent and reverse type 2 diabetes naturally. Greystone Books (Vancouver/Berkeley).
For anyone interested in diabetes, whether a physician, patient, diabetes researcher, science historian or general reader, I will recommend reading this book, but not believing in it totally. For, the book is very well written in simple and non-technical language that is within reach of a general reader, the arguments are made clear and convincing by simple and apt analogies and a great and attractive promise is offered, that of reversing type 2 diabetes. The text book theory of type 2 diabetes is with us for over four decades now and research in the meanwhile has kept on challenging it every now and then. But, by and large, the diabetes community has been playing ostrich and has kept on ignoring any inconvenient evidence.
Dr Fung does a marvelous job of putting the history together and exposing the flaws and paradoxes in the mainstream classical theory of type 2 diabetes. All his criticisms of the current beliefs are very well articulated and convincing. He makes it clear that the energy balance view is of little use to control obesity, there is no convincing mechanism linking obesity to insulin resistance, high insulin levels precede obesity and insulin resistance, insulin is not the answer to type 2 diabetes, increased blood sugar is only a symptom and not the central cause of all complications and therefore clinical trials aiming at sugar normalization have failed in getting rid of diabetic complications. All these evidences falsifying the textbook theory of type 2 diabetes exist in literature for quite a long time now, but attempts to articulate it to convincingly refute the theory are still inadequate. Dr Fung’s contribution towards this goal is certainly valuable.
However, one reason why the mainstream has not given up the classical theory is that a stronger and more convincing alternative theory is not yet agreed upon. The Diabetes Code tries to do this, but alas, with an almost equally weak case. The hypothesis that the book proposes has been around for quite some time and being aggressively promoted by many researchers and authors on various platforms. As the author rightly says, all great stories need a villain. For over thirty years fat was the villain, now sugar is trying to replace fat in this important social role. With fat in this role, a very nice-looking logical story was created on how fat drives type 2 diabetes. The only problem was that this story was not supported by evidence. Now an equally attractive story is created with sugar, and it is time to examine how well it is supported by evidence. Before we look for evidence, the new story already has many flaws and unanswered questions, some of which are addressed in the book with some “explainawaytions”, others are smartly avoided. For example it is not only sugar that induces insulin response, many amino acids also induce it. This well-known phenomenon needs to be incorporated in the theory too. In the entire field of obesity and diabetes, it has been a habit to cherry-pick convenient evidence and the author is faithful to this tradition too. For example, the author asserts that fat in muscle tissue leads to muscle insulin resistance. But data on endurance athletes show that they have high levels of intramuscular fat and still are insulin sensitive. This is not accounted for by the theory. Similarly, explanations are weak on why only refined sugars (and not all carbohydrates) lead to high insulin response, why the principle of ‘high exposure creates resistance’ does not apply to the ill-effects of insulin, or if insulin is the main culprit then why the complications of diabetes still progress when in advanced stages of type 2 diabetes the insulin levels come down substantially. There is increasing evidence that the central nervous system plays a role in the regulation of energy as well as that of insulin response, but the book pretends as if the central nervous system does not exist.
Now about evidence. As I was enjoying reading the book, I received news alerts about a debate on whether sugar induced insulin is the driver of diabetes, published in the journal JAMA Internal Medicine. There were enthusiastic promoters of the story in the debate but an equal number of skeptics who did not find the current evidence convincing enough. It is fair to say that take the “sugar-villain” hypothesis seriously and research more on it. But instead the author paints it as an established truth and guaranteed formula to cure type 2 diabetes. By the way, fat and sugar are not the only rival villains, various other components of diet such as red meat, acidic foods, refined foods; eating habits such as frequent eating, twice a day or once a day eating, skipping or not skipping breakfast, are all being blamed by different champions and each one of them claim to have evidence.
There was a similar episode in the history of medicine about a hundred years ago. When vitamin deficiencies and their effects were not well known, two diseases, namely beriberi and pellagra, were being investigated. Since germ theory of disease was well established by then and was very successful, a large number of groups kept on isolating different bacteria and claimed them to be the causal agents. This mad race continued till the entirely new paradigm of vitamin deficiency disorders emerged. Today we see a similar race in the field of diabetes. Diet is an accepted paradigm and various components of diets are being blamed by different groups, some have a stronger voice than others, but all are equally weak in evidence. We will have to wait and see whether history repeats and an entirely new paradigm in medicine emerges.
Milind Watve is a Professor at Indian Institute of Science Education and Research Pune and is the author of the book “Doves, Diplomats and diabetes: a Darwinian interpretation of type 2 diabetes and related disorders”.