Diet in diabetes
A diabetic diet is a diet that is used by people with diabetes mellitus or high blood sugar to minimize symptoms and dangerous complications of long-term elevations in blood sugar.
Among guideline recommendations including the American Diabetes Association and Diabetes UK, there is no consensus that one specific diet is better than others. This is due to a lack of long term high-quality studies on this subject.
For overweight and obese people with diabetes, the most important aspect of any diet is that it results in loss of body fat. Losing body fat has been proven to improve blood glucose control and lower insulin levels.
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. Likewise, people with diabetes may be encouraged to reduce their intake of carbohydrates that have a high glycemic index, although the ADA and Diabetes UK note that further evidence for this recommendation is needed.
Diet composition
General
People with diabetes can eat any food that they want, preferably a healthy diet with some carbohydrates, but they need to be more cognizant of the carbohydrate content of foods and avoid simple sugars like juices and sugar-sweetened beverages. For people dependent on insulin injections, it is helpful to eat a consistent amount of carbohydrate to make blood sugar management easier.Macronutrients
As of 2019 there was no consensus that eating a diet consisting of any particular macronutrient composition is more beneficial for diabetics. However, research on diabetic diets is limited due to the difficulty of nutritional research. These studies tend to be observational as opposed to experimental, relatively short in duration, and have relatively poor compliance due to the difficulty of controlling the diets of study participants at all hours of the day for extended periods of time. Thus, more large-scale multi-center trials are needed to improve diet recommendations.Carbohydrates
s include sugars, starches, and fiber. These foods have the greatest impact on blood sugar levels, because after consumption they are broken down into sugars that are then absorbed by the small intestine.The American Diabetes Association does not recommend a specific amount of carbohydrate consumption for diabetic diets. Although it is recommended to not use fructose as an added sweetener because it may adversely affect plasma lipids. There is no minimum required amount of daily dietary carbohydrates as the body can make glucose through various metabolic processes including gluconeogenesis and glycogenolysis. The same is not true of protein and fat as both contain essential components that cannot be synthesized through human metabolism.
The ADA addresses the glycemic index and glycemic load of foods pertaining to diabetics, but they decline to make specific recommendations due to the unclear clinical utility. However, meta-analyses including the most recent Cochrane Systematic Review have found that a low glycemic index diet results in better blood glucose control as measured by glycated hemoglobin A1c as well as fewer hypoglycemic episodes.
Fiber
Benefits may be obtained by consumption of dietary fiber. There is some evidence that consuming dietary fiber may help control blood sugar levels; however, the ADA does not recommend any different fiber intake for diabetics than for non-diabetics.Fats
The ADA does not make a specific recommendation about the total amount of fat that should be consumed by diabetics on a daily basis. They do note that studies have shown that high fat diets that have replaced carbohydrates with fat have shown improved glycemic control and improved blood lipid profiles compared to low fat diets. The ADA recommends avoiding all foods that have artificial sources of trans fats but note that the small amount of trans fats that naturally occur in meat and dairy are not a concern.Cholesterol
As at 2019 the ADA does not have a specific recommendation for dietary cholesterol intake. A causal link between dietary cholesterol consumption and cardiovascular disease has not been established.Protein
Historically, there has been concern about the level of protein consumption in individuals who have diabetes induced kidney disease; however, there is no evidence that low protein diets improve kidney function. There is no evidence that individuals with diabetes induced kidney disease need to restrict protein intake more than an average person's intake.Specific diets
Low-carbohydrate diet
For type 1 diabetics, there is a lack of definitive evidence of the usefulness of low-carbohydrate diets due to limited study of this topic. A meta-analysis published in 2018 found only nine papers that had adequately studied the implementation of low carbohydrate diets in type 1 diabetics as of March 2017. This review found that low carbohydrate diets consistently reduced insulin requirements but found inconsistent results in regard to the diet's effect on blood glucose levels. 3 studies found significant decreases in HbA1c on low carbohydrate diets while 5 found that HbA1c levels were stable. This review as well as the ADA consensus statement suggests that low carbohydrate diets may be beneficial for type 1 diabetics but larger clinical trials are needed for further evidence.A low-carbohydrate diet gives slightly better control of glucose metabolism than a low-fat diet in type 2 diabetes. In a 2019 consensus report on nutrition therapy for adults with diabetes and prediabetes the American Diabetes Association states "Reducing overall carbohydrate intake for individuals with diabetes has demonstrated the most evidence for improving glycemia and may be applied in a variety of eating patterns that meet individual needs and preferences.", it also states that reducing overall carbohydrate intake with low- or very low- carbohydrate eating plans is a viable approach. In fact, some investigations say that patients adhering to an low carbohydrate diet may experience remission of diabetes type 2 without adverse consequences
The ADA say low-carbohydrate diets can be useful to help people with type 2 diabetes lose weight, but that these diets were poorly defined, difficult to sustain, unsuitable for certain groups of people and that, for diet composition in general". Overall, the ADA recommends people with diabetes develop "healthy eating patterns rather than focusing on individual macronutrients, micronutrients, or single foods". They recommend that carbohydrates in a diet should come from whole food sources such as "vegetables, legumes, fruits, dairy, and whole grains"; highly refined foods and sugary drinks should be avoided.
Vegan/vegetarian
Although vegan and vegetarian diets can vary greatly in the type of food consumed as well as the macronutrient profile of the diet, they are often lumped together in the context of the scientific literature since they are both considered plant-based diets. Like any other diet's impact on diabetes, the most important factor is the resulting loss of overall fat mass. Both vegan and vegetarian diets have been shown to be beneficial for weight loss in comparison to the standard American diet. For type 2 diabetics, the focus of a vegetarian or vegan diet should be maintaining a level of caloric intake that results in fat loss, adequate protein consumption, adequate consumption of compounds that are most bio-available in animal products, and whole food carbohydrate sources that are lower in glycemic index.The Academy of Nutrition and Dietetics maintains that well formulated vegetarian and vegan diets can be healthy and nutritionally adequate for people of all ages. The American Diabetes Association notes that the use of vegetarian or vegan diets for diabetes have had inconclusive results in the literature. Two meta-analyses showed small improvements in HbA1C; whereas, one of the two found that the diets resulted in weight loss and improvement in cardiovascular risk factors.
Low glycemic index diet
Lowering the glycemic index of one's diet may improve the control of diabetes. This includes avoidance of such foods as potatoes cooked in certain ways and bread. Lower glycemic index carbohydrate sources include vegetables, legumes, and whole grains that contain higher fiber content and are digested and absorbed into the blood stream more slowly than refined carbohydrates.High fiber diet
The ADA recommends a level of fiber intake consistent with the . However, there is some evidence that higher intakes, can result in small improvements in blood sugar levels. The ADA cautions that higher intakes may cause digestive issues such as "flatulence, bloating, and diarrhea."Timing of meals
For people with diabetes, healthy eating is not simply a matter of what one eats, but also when one eats. For insulin dependent diabetics, when they eat depends on their blood sugar level and the type of insulin they take. If patients check their blood glucose at bedtime and find that it is low, for example below 6 millimoles per liter, 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. 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, obesity and other factors that reduce the risk of developing type 2 diabetes. The ADA notes that several studies have shown benefit of intermittent fasting on blood sugar control. However, these studies were relatively small and short in duration and further study is warranted. There were also different protocols for fasting which makes comparisons across studies more difficult.