Diet, delusion and diabetes

Abstract

Diet is good for diabetes, as everyone agrees, but which diet? The word itself has acquired such negative associations that professionals now prefer to talk of medical nutrition therapy, abbreviated to MNT to avoid the negative connotations of the word ‘nutrition’. Shakespeare said that ‘a rose by any other name would smell as sweet’, but it will still have thorns, and we will continue to call a diet a diet. Three related health benefits might be expected from a diet for diabetes: improved metabolic control, weight loss, and reduced risk of vascular disease. From a patient’s point of view, you diet because you want to lose weight, a desire typically expressed in the future conditional, as in ‘I really must think about going on a diet’. Overweight cannot be divorced from emotion, and its consequences cannot be measured in kilograms, for its true costs to the individual must be paid in the currency of the soul. Let us therefore ask a much simpler question: weight loss apart, which diet is best for diabetes? The recent American Diabetes Association (ADA) guidelines, drafted in the light of 150 years of experience in the dietary management of diabetes, conclude that we lack the evidence needed to reach a conclusion [3]. Will we ever find the right answer? Or are we asking the wrong questions? From an historical perspective, it is easy to see that the investigators of diet have confused circular motion with progress. The very low carbohydrate diets of the pre-insulin era yielded to the high carbohydrate diets of the late 1920s and 1930s, and these gave way to the free diets of the 1930s through to the 1950s. The cycle then resumed with the low carbohydrate diet of the 1960s, the high carbohydrate/high fibre diet of the 1970s, the free diets of the latter part of the century and the reincarnation of the pre-insulin regimen in the form of the Atkins diet. The enthusiasts have come and gone, each claiming unique virtue and spectacular success for their own particular regimen, and it would be hard to imagine a diet that has not at some stage constituted an article of faith in diabetes management. Almost all these diets worked some of the time, but we may suspect that few were followed with any degree of rigour for most of the time. Diabetologia (2009) 52:1–7 DOI 10.1007/s00125-008-1203-9