History of Nutrition Therapy for Diabetes
No pharmacotherapy was available for the treatment of type 1 diabetes mellitus (T1DM), until the discovery of insulin in 1921. Before the discovery of insulin, the only treatment options were the starvation diet (proposed by Dr. Frederic Allen) or the extremely low-carbohydrate diet (proposed by Dr. Elliot Joslin).
In 1922, insulin became available, and T1DM became treatable. Thereafter, with the initiation of insulin, the starvation diet fell out of use and the low-carbohydrate diet was recommended less frequently.
In 1971, a special report on Principles of Nutrition and Dietary Recommendations for Patients with Diabetes Mellitus was published by the first American Diabetes Association (ADA) Dietary Guidelines. In this special report, ADA mentioned that there is no longer any need to restrict disproportionately the intake of carbohydrates in the diet of most diabetic patients.
Nutrition therapy for diabetes in the late 20th century
Nutrition therapy for the management of diabetes entered a new phase by 1970s. There was a major health concern worldwide due to the increase in the prevalence of type 2 diabetes mellitus (T2DM) and its complications. Due to this epidemic, the prevention of cardiovascular disease in patients with T2DM received more attention than the glycemic control of patients with T1DM, leading to a greater interest in nutrition therapy.
The Seven Countries Study was designed to investigate the relationship between diet and cardiovascular disease. It was reported that saturated fat was strongly correlated with long-term CHD mortality. This finding led to a general belief that a low-fat diet was useful for the prevention of cardiovascular deaths.
The Seven Countries Study included four Mediterranean cohorts: Crete and Corfu in Greece, Dalmatia in Croatia and Montegiorgio in Italy. In the 1960s the Greek diet had the highest content of olive oil and was high in fruit, the Dalmatian diet was highest in fish and the Italian diet was high in vegetables. In line with their diet, these cohorts were characterized by low mortality rates from CHD
In addition, a randomized controlled trial conducted in the 1970s did not find an association between the low-fat diet and reduced total mortality or cardiovascular mortality. Despite these negative findings, the McGovern Report was published in 1977, and the importance of the low-fat diet was increasingly emphasized in the United States.
In response, the ADA revised their recommendations in 1979, emphasizing the importance of the low-fat diet. The ADA recommended that carbohydrate intake should make up 50–60% of the total energy intake, whereas, in 1971, it recommended that carbohydrate intake should not exceed 45% of the total energy intake. This change occurred when the liberalization of carbohydrate intake was being more widely suggested.
Current nutrition therapy for diabetes
As mentioned above, the benefits of carbohydrate restriction were de-emphasized in the 1979 ADA guidelines; however, the clinical significance of the low-carbohydrate diet continued to be recognized as the Atkins diet for obesity and the Bernstein diet for diabetes became prevalent in the field of popular medicine. The A TO Z Weight Loss Study was scientifically designed to test the effectiveness of Atkins, Zone, Ornish, and LEARN Diets. This study demonstrated that the Atkins diet was the most effective for treating obesity.
In 2008, the Dietary Intervention Randomized Controlled Trial (DIRECT) reported that the low-carbohydrate diet was the most effective for improving hemoglobin A1c (HbA1c) levels in patients with diabetes. Furthermore, subsequent subanalyses showed that the improvement in body weight and lipid profiles induced by the low-carbohydrate diet was maintained for up to 6 years.
In 2012, a systematic review and meta‐analysis were carried out to study the effects of a low‐carbohydrate diet on weight loss and cardiovascular risk factors. A total of 23 reports, corresponding to 17 clinical investigations, were identified as meeting the pre‐specified criteria. The results showed that the low-carbohydrate diet had positive effects not only on blood glucose, lipid profiles (in particular, high-density lipoprotein cholesterol and triglycerides), and body weight but also on blood pressure.
In response to these findings, the ADA guidelines in 2013 recommended the low-carbohydrate diet as a first-choice treatment for diabetes.
Diets currently considered useful for managing diabetes
Includes abundant plant-based food, olive oil as the principal source of dietary lipids, dairy products consumed in low to moderate amounts, low red meat consumption, and low to moderate wine consumption.
Emphasizes fruits, vegetables, and low-fat dairy products and includes whole grains, poultry, fish, and nuts. Reduced consumption of saturated fat, red meat, sweets, and sodium.
Avoids all animal flesh-based foods and animal-derived products. Some modified versions allow eggs (ovo) and/or dairy products (lacto).
Carbohydrate intake reduced to 20–40 g/meal with sweets containing 10 g of carbohydrate per day.