A diabetic diet or diabetes diet is a diet that is used by people with diabetes mellitus or high blood glucose to minimize symptoms and dangerous consequences of the disease.
Since carbohydrate is the macronutrient that raises blood glucose levels most significantly, the greatest debate is how low in carbohydrates the diet should be. This is because although lowering carbohydrate intake will help reduce blood glucose levels, a low-carbohydrate diet conflicts with the traditional establishment view that carbohydrates should be the main source of calories. Recommendations of the fraction of total calories to be obtained from carbohydrate are generally in the range of 20% to 45%, but recommendations can vary as widely as from 16% to 75%.
For overweight and obese people with Type 2 diabetes, any weight-loss diet that the person will adhere to and achieve weight loss on is at least partly effective.
The most agreed-upon recommendation is for the diet to be low in sugar and refined carbohydrates, while relatively high in dietary fiber, especially soluble fiber. People with diabetes are also encouraged to eat small frequent meals a day. Likewise, people with diabetes may be encouraged to reduce their intake of carbohydrates that have a high glycemic index (GI), although this is also controversial. (In cases of hypoglycemia, they are advised to have food or drink that can raise blood glucose quickly, such as a sugary sports drink, followed by a long-acting carbohydrate (such as rye bread) to prevent risk of further hypoglycemia.) Others question the usefulness of the glycemic index and recommend high-GI foods like potatoes and rice. It has been claimed that oleic acid has a slight advantage over linoleic acid in reducing plasma glucose.
There has been long history of dietary treatment of diabetes mellitus. Dietary treatment of diabetes mellitus was used in Egypt since 3,500 BC and was used in India by Sushruta and Charaka more than 2000 years ago. In the 18th century, John Rollo argued that calorie restriction could reduce glycosuria in diabetes.
More modern history of the diabetic diet may begin with Frederick Madison Allen and Elliott Joslin, who, in the early 20th century, before insulin was discovered, recommended that people with diabetes eat only a low-calorie and nearly zero-carbohydrate diet to prevent ketoacidosis from killing them. While this approach could extend life by a limited period, patients developed a variety of other medical problems.
The introduction of insulin by Frederick Banting in 1922 allowed patients more flexibility in their eating.
In the 1950s, the American Diabetes Association, in conjunction with the U.S. Public Health Service, introduced the "exchange scheme". This allowed people to swap foods of similar nutrition value (e.g., carbohydrate) for another. For example, if wishing to have more than normal carbohydrates for dessert, one could cut back on potatoes in one's first course. The exchange scheme was revised in 1976, 1986, and 1995.
Not all diabetes dietitians today recommend the exchange scheme. Instead, they are likely to recommend a typical healthy diet: one high in fiber, with a variety of fruit and vegetables, and low in both sugar and fat, especially saturated fat.
A diet high in plant fibre was recommended by James Anderson. This may be understood as continuation of the work of Denis Burkitt and Hugh Trowell on dietary fibre, which may be understood as a continuation of the work of Price. It is still recommended that people with diabetes consume a diet that is high in dietary fiber.
In 1976, Nathan Pritikin opened a centre where patients were put on programme of diet and exercise (the Pritikin Program). This diet is high on carbohydrates and fibre, with fresh fruit, vegetables, and whole grains. A study at UCLA in 2005 showed that it brought dramatic improvement to a group of people with diabetes or pre-diabetes in three weeks, so that about half no longer met the criteria for the disease.
On the other hand, in 1983, Richard K. Bernstein began treating people with diabetes and pre-diabetes successfully with a very low-carbohydrate diet, avoiding fruit, added sugar, and starch. Both the Pritikin approach and the Bernstein approach prescribe exercise.
An approach that has been popular with some people with type 1 diabetes mellitus since 2000 is known as DAFNE (Dose Adjustment for Normal Eating). This approach involves estimating the amount of carbohydrates in a meal and modifying the amount of insulin one injects accordingly. An equivalent approach has for people with type 2 diabetes mellitus is known as DESMOND, which stands for Diabetes Education and Self-Management for On-Going and Newly Diagnosed (diabetes). DAFNE has a newsletter and has received recommendation.
The American Diabetes Association in 1994 recommended that 60–70% of caloric intake should be in the form of carbohydrates. As mentioned above, this is controversial, with some researchers claiming that 40% or less is better, while others claim benefits for a high-fiber, 75% carbohydrate diet.
An article summarizing the view of the American Diabetes Association contains the statements:
- "Sucrose-containing foods can be substituted for other carbohydrates in the meal plan or, if added to the meal plan, covered with insulin or other glucose-lowering medications. Care should be taken to avoid excess energy intake."
- Sucrose does not increase glycemia more than the same number of calories taken as starch.
- It is not recommended to use fructose as a sweetener because it may adversely affect plasma lipids.
- Benefits may be obtained by consumption of dietary fiber.
Francis points out, evidence suggests that carbohydrate consumed with dietary fiber will have a lower impact on glycemic rise than the same amount of carbohydrate consumed alone. Due to their high levels of dietary fibre, certain foods are considered particularly beneficial for people with diabetes such as legumes, nuts, fruits, and vegetables.
What has not generally been included in diabetic diet recommendations is the variation in effect from different carbohydrates. It has been recommended that carbohydrates eaten by people with diabetes should be complex carbohydrates.
A low-carbohydrate diet or low-glycemic diet can be an effective dietary option for managing type 2 diabetes. These have been promoted as working by reducing spikes in blood sugar levels after eating. However, the main contribution may be that overweight and obese people with Type 2 diabetes often lose weight while following these diets. Any diet that causes significant weight loss in overweight and obese people with Type 2 diabetes is associated with improvements in blood sugar control.
Richard K. Bernstein is critical of the standard American Diabetes Association diet plan. His plan includes very limited carbohydrate intake (30 grams per day) along with frequent blood glucose monitoring, regular strenuous muscle-building exercise and, for people using insulin, frequent small insulin injections if needed. His treatment target is "near normal blood sugars" all the time.
Another critic of the ADA program is futurologist and transhumanist Ray Kurzweil, who with Terry Grossman co-authored Fantastic Voyage: Live Long Enough to Live Forever (published 2004). They describe the ADA guidelines as "completely ineffective". Their observations are that the condition, particularly in its early stages, can be controlled through a diet that sharply reduces carbohydrate consumption. Their guidelines for patients with type 2 diabetes is a diet that includes a reduction of carbohydrates to one sixth of total caloric intake and elimination of high glycemic load carbohydrates. As someone who was diagnosed with diabetes but who no longer has symptoms of the disease, Kurzweil is a firm advocate of this approach. However, Kurzweil's prescription changed somewhat between his 1993 book The 10% Solution for a Healthy Life, in which he recommended that only 10% of calories should come from fat, and Fantastic Voyage, which recommends 25%.
Based on the evidence that well planned vegan diets can be lower in unhealthy processed foods than the standard American diet, some studies have investigated vegan interventions as a possible treatment for Type 2 Diabetes. These studies have shown that a vegan diet may be effective in managing type 2 diabetes. Plant-based diets tend to be higher in fiber, which slows the rate sugar is absorbed into the bloodstream. Additionally, simple carboydrates, abundant in processed foods, which are often not vegan, have the potential to elevate HbA1c levels more than other healthier foods. In multiple clinical trials, participants who were placed on a vegan diet experienced a greater reduction in their Hemoglobin A1c levels than those who followed the diet recommended by the ADA.
The American Diabetes Association has released a statement declaring a vegan diet to be a healthful option for all ages. In the ADA's 2018 Standards of Medical Care in Diabetes, a vegan diet was even included as a treatment option. Diabetes UK agrees, and has stated that diabetes should not prevent people from going vegetarian – in fact, it may be beneficial for people with diabetes to go vegetarian, as this will cut down on saturated fats.
In one meta analysis done in 2017, the authors agreed on the possibility of a vegetarian diet having preventative effects on Type 2 Diabetes development; however, they concluded that more research on this field needs to be conducted. Another meta analysis that included twelve cohort studies concluded that red meat consumption is associated with an increased risk of Type 2 Diabetes. A third meta analysis done in 2013 that compared a variety of different diets' effects on health concluded that a plant based diet high in whole foods, and with limited processed foods can be beneficial for the treatment and prevention of Type 2 Diabetes.
Timing of meals
For people with diabetes, healthy eating is not simply a matter of "what one eats", but also when one eats. The question of how long before a meal one should inject insulin is asked in Sons Ken, Fox and Judd (1998). It depends upon the type one takes and whether it is long-, medium- or quick-acting insulin. If patients check their blood glucose at bedtime and find that it is low, for example below 6 millimoles per liter (108 mg/dL), it is advisable that they take some long-acting carbohydrate before retiring to bed to prevent night-time hypoglycemia. Night sweats, headaches, restless sleep, and nightmares can be a sign of nocturnal hypoglycemia, and patients should consult their doctor for adjustments to their insulin routine if they find that this is the case. Counterintuitively, another possible sign of nocturnal hypoglycemia is morning hyperglycemia, which actually occurs in response to blood sugar getting too low at night. This is called the Somogyi effect.
In relation to type 2 diabetes, eating most food earlier in the day may be associated with lower levels of overweight and obesity and other factors that reduce the risk of developing type 2 diabetes.
Special diabetes products
Diabetes UK have warned against purchase of products that are specially made for people with diabetes, on grounds that:
- They may be expensive
- They may contain high levels of fat
- They may confer no special benefits to people who have diabetes
It should be noted that NICE (the National Institute for Health and Clinical Excellence in the United Kingdom) advises doctors and other health professionals to "Discourage the use of foods marketed specifically for people with diabetes".
Research has shown the Maitake mushroom (Grifola frondosa) has a hypoglycemic effect and may be beneficial for the management of diabetes. Maitake lowers blood sugar because the mushroom naturally acts as an alpha glucosidase inhibitor. Other mushrooms like lingzhi, Agaricus blazei, Agrocybe cylindracea and Cordyceps have been noted to lower blood sugar levels to a certain extent, although the mechanism is currently unknown.
Alcohol and drugs
Moderation is advised with regard to consuming alcohol and using some drugs. Alcohol inhibits glycogenesis in the liver and some drugs inhibit hunger symptoms. This, with impaired judgment, memory and concentration caused by some drugs can lead to hypoglycemia. People with diabetes who take insulin or tablets such as sulphonylureas should not, therefore, consume alcohol on an empty stomach but take some starchy food (such as bread or potato crisps) at the same time as consumption of alcohol.
Specific diabetes diets
- The Pritikin Diet consists of fruit, vegetables, whole grains, and so on, and is high in carbohydrates and roughage. The diet is accompanied by exercise.
- G.I. Diet: lowering the glycemic index of one's diet can improve the control of diabetes. This includes avoidance of such foods as potatoes cooked in certain ways and white bread. It instead favors multi-grain and sourdough breads, legumes and whole grains that are converted more slowly to glucose in the bloodstream.
- Low Carb Diet: It has been suggested that the removal of carbohydrates from the diet and replacement with fatty foods such as nuts, seeds, meats, fish, oils, eggs, avocados, olives, and vegetables may help reverse diabetes. Fats would become the primary calorie source for the body, and complications due to insulin resistance would be minimized.
- High fiber diet: It has been shown that a high fiber diet works better than the diet recommended by the American Diabetes Association in controlling diabetes and may control blood sugar levels with the same efficacy as oral diabetes drugs.
- The Paleolithic diet has been shown to improve glucose tolerance in people with diabetes type 2, ischemic heart disease and glucose intolerance, and in healthy pigs.
- A low-fat vegan diet improves glycemic control similar to the ADA diet.
- The American Diabetes Association has endorsed a natural foods approach to managing diabetes, advocating “fresh is best” and avoiding artificial sweeteners, instead substituting measured amounts of fresh fruit or raw sugar.