What is the best diet for patients with diabetes.

individual approach. Modifying a diet should lead to an improvement in health markers, but it also has to suit the patient so that they are able to adhere to the diet in the long-term. Various dietary approaches (common balanced diet, Mediterranean, vegetarian, and others) can have a positive effect on improving glycaemic control, but they should always be based on quality foods and without added sugars. 

Here we will explain the principles of the so-called low carb diet. It has recently become more popular, as both research and practice have highlighted its benefits also in the treatment of diabetes.

The fundamental issue in diabetes is the inability to maintain a normal level of blood glucose, the primary source of which are carbohydrates in food. In Type 1 Diabetes, lowering carbohydrate intake will require patients to use lower doses of insulin, and result in lower glycaemic variability and reduced risk of hypoglycemia. It makes it much easier to calculate the doses of mealtime insulin. It allows patients with Type 2 Diabetes to reduce doses of medications including insulin and, in a number of cases, can lead to deprescribing (discontinuation).

In overweight or obese patients, it also helps to reduce weight. A lower intake of carbohydrates means a lesser need for insulin and thus limited growth of fat deposits. Insulin is a storage hormone that has the tendency to deposit all unnecessary nutrients in energy stores. Excessive fat stores decrease the effect of insulin, which in turn needs to be secreted in greater doses – this creates a vicious cycle and complicates the treatment of diabetes.

Increased levels of insulin hinder the utilization of fat deposits and, with a diet primarily consisting of carbohydrates, insulin levels are increased throughout much of the day. Injection insulin works in the same way, and therefore insulin therapy combined with a regular diet makes it more difficult to lose weight and easier to gain weight.

A lower intake of carbohydrates requires less insulin and a lower insulin level makes it easier for the body to utilize its own fat stores. When carbohydrate intake is reduced, patients with diabetes are more successful at getting rid of extra kilograms. High-quality fats and proteins together with vegetables are more filling than meals full of carbohydrates and are digested more slowly and thus more naturally. Without hunger pangs, they make it possible to eat less at a generally lower caloric intake.

What is a low-carb diet?

A low-carb diet follows several basic rules:


There are several types of low-carb diet based on carbohydrate intake.

The strictest form contains only 30 – 50 g of carbohydrates per day, primarily in the form of non-sweet vegetables. It is usually used for shorter periods of time to reach a certain goal – to reduce weight and improve glycaemic control in diabetes. Adhering to this diet in the long term may be difficult for many patients, and therefore they can shift to a less strict option once they have achieved their goal.  

The version with an intake of around 60 – 80 g carbohydrates per day is more diverse, and can include sweeter vegetables, more fruit, sometimes a piece of high-quality bread, or legumes.

A moderate low-carb diet contains around 100 g (max. 130 g) of carbohydrates per day. This amount can include even smaller portions of common side dishes that contain carbohydrates. However, in order to maintain good results, the basic principles mentioned above still apply – carbohydrates that are included in the diet should not be in the form of sweets and other sources of free sugars; smaller portions of side-dishes should also be made from high-quality ingredients (i.e. sourdough, not white bread), legumes, and whole-grain cereals. A higher intake of fat may be a downside of the moderate option. With the strict option, fat intake does not have to be “watched” – i.e. nobody overeats butter or lard alone. With the moderate low-carb option, there is a risk that carbohydrate intake moderately decreases, but at the same time the intake of fats significantly increases. Such a diet would lead to weight gain and worsen diabetes.

In Type 2 Diabetes, a low-carb diet is a way to maintain an optimal blood sugar level, sometimes without the need for medications. If you are already using medications or being treated with insulin, you should inform your doctor about your dietary changes, as your medication therapy may not be compatible with a low-carb diet. After a change in diet, dosage of some medications need to be lowered and some should be discontinued altogether in order to prevent hypoglycemia and other complications.

In Type 1 Diabetes, this diet allows mealtime insulin doses to be reduced. Modification of medications must also be consulted with a doctor. Dosage of long-acting/basal insulin usually stays the same. But be careful – stopping insulin in a patient with Type 1 Diabetes would result in ketoacidosis! </span

Low-carb diets significantly help in the treatment of diabetes, but some groups of patients should consider the degree and form of the diet. This includes children with Type 1 Diabetes and pregnant or breastfeeding women. The diet can also be unsuitable for patients with diabetes who have kidney disease – they must monitor and not exceed their recommended intake of protein. A low-carb diet is unsuitable for patients with chronic pancreatitis and other general pancreatic disorders due to issues with fat digestion.

The moderate low-carb diet option that excludes added sugars and refined carbohydrates can be used for children with Type 1 Diabetes. However, pediatricians warn against stricter versions due to a lack of practical experience and data from long-term observational studies. A poorly managed low-carb diet in children can result in growth stunting or growth slowdown and other complications. Stricter versions of a low-carb diet therefore require medical supervision and cooperation with a nutritional therapist. The diet has to contain a sufficient amount of calories, and an adequate intake of protein is also very important.

Pregnant women who adopted a low carbohydrate diet before pregnancy can continue without worry. If they are considering such a diet, pregnancy and breastfeeding is not a good time for a radical change in diet, and therefore dramatic changes in dietary habits (e.g. a strict ketogenic diet) are not recommended. However, no objections can be raised against the moderate version, which excludes added sugars and refined carbohydrates for pregnant and breastfeeding women. In fact, such a diet can serve as a suitable prevention against gestational diabetes.


What foods make up a low-carb diet

For low-carb diets, it is important to eat real food (i.e. whole foods and minimally processed foods) and exclude ultra processed food products containing added sugars, starches, flour, low-quality processed fats and other added substances.

A diet of a patient with diabetes should primarily include:

1. Non-sweet vegetables in fresh, pickled and cooked form (boiled in water or steamed, sauteed, baked). Vegetables can be a part of every meal and can thus replace a traditional carbohydrate-based side dish. Vegetables can be seasoned with high-quality oil, unsweetened vinegar or lemon juice; cooked vegetables can be seasoned with butter, meat drippings, etc.

Vegetables that can be eaten without limitations are: Zucchini, chicory (radicchio), garlic, Chinese cabbage, fennel, pickled cabbage, lettuces, chard, cucumber, squash, chives, leeks, rhubarb, spinach, spring onions, green beans, and green asparagus.

Relatively low amounts of carbohydrates are contained in onions, fruiting vegetables (tomatoes, sweet peppers, eggplant), broccoli, borecole kale, cauliflower, cabbage, kohlrabi, celery, turnips, radishes, white asparagus and Jerusalem artichokes – for patients on insulin, however, carbohydrates need to be counted when consuming a larger amount of these vegetables (100 or more grams).

2. Mushrooms: White mushrooms, oyster mushrooms and others, as they do not contain significant amounts of carbohydrates.

3. Nuts and seeds: These are a source of high-quality fats and proteins, fiber, vitamins and minerals and should certainly be a part of a diet. They do, however, also contain carbohydrates (especially cashews), and nuts should therefore not be consumed in amounts over 100 g per day.
Fats contained in nuts are degraded when roasted, and therefore unroasted, unsalted nuts are best, although light roasting at home or dry baking may improve their digestibility. Soaking nuts in water overnight can also improve their taste and make it easier for older people to chew them.

4. High-quality fats: Only high-quality fats should be chosen, such as butter, clarified butter (ghee), cream, bacon, lard, cold-pressed oils (olive, avocado), homemade mayonnaise (without sugar), high-quality coconut oil, seeds, nuts, nut butters, avocados, coconuts, and olives. Industrially processed fats should be avoided (i.e. margarines, hardened or partially hardened fats).
Fat carries taste and is satiating, and thanks to a sufficient intake of fats you will not feel hungry on a low-carb diet. Fats are also a source of important vitamins (D, E, K, A) and essential fatty acids.
A good way to ensure a sufficient intake of fats in your diet is to add them to vegetables or at the end of meal preparation (butter in soup, meat drippings added to meals, etc.).

5. Meats and organs: Red and white meat, including fatty meat (pork belly), chicken including the skin, liver and other organs. Battered and fried meats are problematic due to the carbohydrates in the flour and breading (one serving of fried chicken contains 15-20g of carbohydrates).
Meat is a rich source of protein, and therefore one serving a day should be sufficient. Cut back on smoked meats (as they are highly salty and contain harmful nitrites) and select only high-quality meats (ham off the bone, high-quality bacon, etc.). Hot dogs, pepperonis, low-quality sausages, meat spreads, salamis and other ultra processed meat products are not suitable in a low-carb diet – they are often made from low-quality ingredients and contain sugar, starch, large amounts of sodium and a number of additives.

6. Fish: Fatty fish such as salmon, mackerel or eel should be given preference. If fresh fish is not available, canned fish can also be used, but only containing fish in brine or in oil without other problematic additives.

7. Eggs: Eggs can be eaten daily and without worrying about cholesterol. Eggs and hundreds of recipes on how to prepare them offer an easy and quick way to fix a meal.

8. Cheeses: Just like meat, hard cheeses are a rich source of protein, and therefore should be eaten in moderate amounts. In terms of cheese spreads, processed cheeses should be avoided (as they contain problematic emulsifying salts) and products thickened with starch (some types of fresh dairy or cheese spreads).

9. Fermented dairy products: Yogurt, quark/cottage cheese, sour cream, kefir, buttermilk, acidophilus milk, etc. Always give preference to unsweetened products. These products can be seasoned with nuts, seeds and a small amount of fruit. It is good to avoid low-fat dairy products, as they contain more carbohydrates (i.e. they are often thickened with starch) and are nutritionally inferior. Do not drink plain milk in excess (200 mL of milk contains 10 g of lactose) – milk significantly raises glycemia in some patients with diabetes.

10. Low-carb “bread”: Regular bread is not suitable on a low-carb diet, but bread (or flatbread) can be made without flour – recipes can be found in the links.
As a last resort, so-called “low-carb” bread and baked goods can be used; these breads are often sold as “evening” breads and have a very low carbohydrate content (up to 10g/100g).

11. Soups: Soups can easily be prepared without carbohydrates. Acceptable soups include cream soups, vegetable soups, or traditional stews with meat and vegetables (but without noodles or dumplings) – soups should not be sweetened or thickened with flour or roux). Soup can be thickened by blending in a portion of the vegetables and seasoning with butter.

How much and how often to eat

The amount of meals eaten throughout the day is individual. For patients who are overweight or obese, it is better to eat a full meal two or three times per day. Snacking and other “nibbling” should be avoided between meals, as sufficient breaks and insulin drops between meals facilitate the desired burning of fat deposits. Weight reduction will also speed up if you do a one-day or half-day fast from time to time.

The number of meals should be higher for slimmer patients with Type 1 Diabetes, children and pregnant or breastfeeding women according to their needs and habits.