Conclusions

• In type 2 diabetes, low-fat and moderate low-carbohydrate diets (30–40% of the energy from carbohydrates) have similar, favorable effects on HbA1c (long-term blood glucose) and bodyweight. The absence of sufficient-quality studies in people with diabetes prevents evaluation of the long-term effects of more extreme diets involving low-carbohydrate and high-fat intake, e.g., so-called “low-carb, high-fat” (LCHF) diets. Hence, safety aspects become particularly important in clinical follow-up of individuals who choose extreme low-carbohydrate diets (10–20% energy from carbohydrates).
• Limited scientific evidence shows that vegetables, legumes, and fish are beneficial for people with diabetes. These foods are important components of the current dietary recommendations in diabetes. The literature review did not reveal evidence for drawing conclusions on other key components of dietary recommendations, e.g., whole grain products and fat content. No scientific evidence has emerged either for or against changing the current dietary recommendations in diabetes.
• People with type 2 diabetes who regularly consume moderate amounts of alcohol have a lower morbidity and mortality from cardiovascular disease than do people who consume no alcohol. Obviously, advice on using alcohol must take into consideration pregnancy or the risk of alcohol abuse. People who drink coffee have a lower risk of cardiovascular disease than those who do not drink coffee.
• So-called “lifestyle intervention”, which combines advice for low-fat, high-fiber diets and increased physical activity, protects against the development of diabetes in people with impaired ability to manage and metabolize glucose (impaired glucose tolerance).
• The absence of sufficient-quality studies prevents evaluation of the importance of the distribution of nutritional intake, or the intake of proteins and whole grain products, throughout the day (24 hours). Also absent are studies addressing the effects of diet on quality of life and on the incidence of eye and renal complications.
• Many studies are under way to evaluate different diets in diabetes. As the results of high-quality studies become available, the conclusions of this report may need to be revised.