Although diet has been debated with considerable zeal and complexity, the basic principles are very simple. In general, the diet considered healthy for members of the general population is healthy for the person with diabetes. This will include restricted use of processed foods, animal fat and sugar, and increased use of fresh fruit and vegetables. Diet should also aim for maintenance of a healthy weight, and food intake needs to be adjusted to match the rate at which insulin enters the blood stream and changing energy requirements during the day. In practice, many people with diabetes achieve successful glucose control with quite varying patterns of food intake, and attention to diet may be more important than its precise content. For example, some people eat freely and adjust the insulin according to the meal they wish to consume. One variant of this approach is known as DAFNE (diet adjustment for normal eating) and, when properly applied, appears to work at least as well as more conventional diets.
Regular controlled food intake is an essential part of the management of type 1 diabetes. This article outlines the principles upon which dietary recommendations for type 1 diabetes have been based, and does not offer detailed advice. Readers seeking this are referred to local and national guidelines (see below for examples).
An individual’s or family’s relationship to food has enormous social and emotional significance. Advice concerning the dietary management of diabetes should therefore be sensitive, realistic, culturally appropriate and designed to suit the lifestyle and preferences of the individual concerned, always bearing in mind that such advice may impact upon the eating behaviour of a whole family. The following points should be kept in mind:
The diet recommended for someone with type 1 diabetes is no different from the healthy diet recommended for the rest of the population. The main practical differences lie in the need to balance food intake against insulin delivery and exercise, and in the avoidance of hypoglycaemia.
Beyond this point, specific dietary recommendations are only weakly based upon good quality evidence. Many of the recommendations come from consensus statements rather than from controlled clinical trials.
As always, when evidence is weak, opinion is strong. Certain routes to dietary salvation may be preached with evangelical fervour, but in practise individuals are able to achieve good glucose control whilst using a wide range of dietary strategies.
Over-elaborate dietary advice may be self-defeating. Simple advice tailored to the needs, motivation and understanding of the individual is the essence of successful therapy. Some people with diabetes develop into highly skilled nutritional experts, but others give up in dismay when overloaded with information.
Before insulin, children with diabetes usually died within 2 years of diagnosis. In 1911, Frank Allen introduced his starvation diet. Rigid discipline was required, and the therapy caused unimaginable anguish to the children and their families. It did however prolong life, allowing some children to survive into the insulin era. Strict carbohydrate restriction was continued following the introduction of insulin, but also meant increased consumption of fat. A high-carbohydrate diet was successfully pioneered in the late 1920s, and some physicians later went on to advocate a free diet. Most physicians still advocated a low carbohydrate intake, however, until the high-carbohydrate diet was rediscovered in the 1960s. Later in the century the low-carbohydrate/high-fat diet, popularised as the Atkins diet, came back into fashion. This (in different versions) still has its advocates, but a high-carbohydrate/low-fat diet remains the standard recommendation.
Energy intake recommendations:
Total daily energy intake should be distributed as follows:
Moderate sucrose intake (up to 10% total energy)
Fat 30–35% (<10% saturated fat + trans fatty acids; <10% polyunsaturated fat; >10% monounsaturated fat (up to 20% total energy); n-3 fatty acids (cis configuration): 0.15 g/day)
General recommendations for healthy eating in diabetes often need to be adapted to specific situations. These include growth and childhood, obesity, sport and leisure activities, pregnancy, hypoglycaemia avoidance, the management of associated conditions such as coeliac disease, and the management of diabetic kidney disease. These are considered in more detail in the sub-sections that follow this article.