Diabetes is a chronic disease that affects many people across the globe.
Currently, more than 400 million people have diabetes worldwide (1).
One of the ways to achieve better blood sugar levels is to follow a low carb diet.
This article provides a detailed overview of very low carb diets for managing diabetes.
What is diabetes, and what role does food play?
With diabetes, the body can’t effectively process carbohydrates.
Normally, when you eat carbs, they’re broken down into small units of glucose, which end up as blood sugar.
When blood sugar levels go up, the pancreas responds by producing the hormone insulin. This hormone allows blood sugar to enter cells.
In people without diabetes, blood sugar levels remain within a narrow range throughout the day. For those who have diabetes, however, this system doesn’t work in the same way.
This is a big problem, because having both too high and too low blood sugar levels can cause severe harm.
There are several types of diabetes, but the two most common ones are type 1 and type 2 diabetes. Both of these conditions can occur at any age.
In type 1 diabetes, an autoimmune process destroys the insulin-producing beta cells in the pancreas. People with diabetes take insulin several times a day to ensure that glucose gets into the cells and stays at a healthy level in the bloodstream (
In type 2 diabetes, the beta cells at first produce enough insulin, but the body’s cells are resistant to its action, so blood sugar remains high. To compensate, the pancreas produces more insulin, attempting to bring blood sugar down.
Over time, the beta cells lose their ability to produce enough insulin (5).
Of the three macronutrients — protein, carbs, and fat — carbs have the greatest impact on blood sugar management. This is because the body breaks them down into glucose.
Therefore, people with diabetes may need to take large doses of insulin, medication, or both when they eat a lot of carbohydrates.
People with diabetes are deficient in insulin or resistant to its effects. When they eat carbs, their blood sugar can rise to potentially dangerous levels unless medication is taken.
Can very low carb diets help manage diabetes?
In fact, before the discovery of insulin in 1921, very low carb diets were considered standard treatment for people with diabetes (
What’s more, low carb diets seem to work well in the long term when people stick to them.
In one study, people with type 2 diabetes ate a low carb diet for 6 months. Their diabetes remained well managed more than 3 years later if they stuck to the diet (
Similarly, when people with type 1 diabetes followed a carb-restricted diet, those who followed the diet saw a significant improvement in blood sugar levels over a 4-year period (
Research has shown that people with diabetes experience long-term improvements in managing blood sugar while eating a low carb diet.
What’s the optimal carb intake for people with diabetes?
The ideal carb intake for people living with diabetes is a somewhat controversial topic, even among those who support carb restriction.
Dr. Richard K. Bernstein, who has type 1 diabetes, has eaten 30 grams of carbs per day and documented excellent blood sugar management in his patients who follow the same regimen (
The optimal amount of carbs may also vary by individual, since everyone has a unique response to carbs.
According to the American Diabetes Association (ADA), there’s no one-size-fits-all diet that works for everyone with diabetes. Personalized meal plans, which take into account your dietary preferences and metabolic goals, are best (17).
The ADA also recommends that individuals work with their healthcare team to determine the carb intake that’s right for them.
To figure out your ideal amount of carbs, you may want to measure your blood glucose with a meter before a meal and again 1 to 2 hours after eating.
As long as your blood sugar remains below 140 mg/dL (8 mmol/L), the point at which damage to nerves can occur, you can consume 6 grams, 10 grams, or 25 grams of carbs per meal on a low carb diet.
It all depends on your personal tolerance. Just remember that the general rule is the less carbs you eat, the less your blood sugar will rise.
Carb intake between 20–90 grams per day has been shown to be effective at improving blood sugar management in people with diabetes. However, it’s best to test blood sugar before and after eating to find your personal carb limit.
Which carbs raise blood sugar levels?
In plant foods, carbs comprise a combination of starch, sugar, and fiber. Only the starch and sugar components raise blood sugar.
Fiber that’s naturally found in foods, whether soluble or insoluble, doesn’t break down into glucose in the body, and doesn’t raise blood sugar levels (18).
You can actually subtract the fiber and sugar alcohols from the total carb content, leaving you with the digestible or “net” carb content. For example, 1 cup of cauliflower contains 5 grams of carbs, 3 of which are fiber. Therefore, its net carb content is 2 grams.
Prebiotic fiber, such as inulin, has even been shown to improve fasting blood sugar and other health markers in people with type 2 diabetes (
Some of them, especially maltitol, can actually raise blood sugar levels in people with diabetes (
For this reason, use the net carb tool cautiously, as the count listed on a product’s label may not be accurate if all the carbs contributed by maltitol are subtracted from the total.
Furthermore, the net carb tool isn’t used by the Food and Drug Administration (FDA) or the ADA.
This carb counter may be a valuable resource. It provides data for hundreds of foods on total carbs, net carbs, fiber, protein and fat.
Starches and sugars raise blood sugar levels, but dietary fiber does not. The sugar alcohol maltitol may also raise blood sugar.
Foods to eat and foods to avoid
It’s best to focus on eating low carb, whole foods with a lot of nutrients.
It’s also important to pay attention to your body’s hunger and fullness cues, regardless of what you’re eating.
Foods to eat
You can eat the following low carb foods until you’re full. Also make sure to get enough protein at each meal:
- meat, poultry, and seafood
- nonstarchy vegetables (most vegetables except those listed below)
- olive oil, coconut oil, butter, cream, sour cream, and cream cheese
Foods to eat in moderation
You can eat the following foods in smaller quantities at meals, depending on your personal carb tolerance:
- Berries: 1 cup or less
- Plain, Greek yogurt: 1 cup or less
- Cottage cheese: 1/2 cup or less
- Nuts and peanuts: 1–2 ounces, or 30–60 grams
- Flaxseeds or chia seeds: 2 tablespoons
- Dark chocolate (at least 85% cocoa): 30 grams or less
- Winter squash (butternut, acorn, pumpkin, spaghetti, and hubbard): 1 cup or less
- Liquor: 1.5 ounces, or 50 grams
- Dry red or white wine: 4 ounces, or 120 grams
Legumes, such as peas, lentils, and beans, are healthy sources of protein, though they do have carbs as well. Be sure to include them in your daily carb count.
Drastically reducing carbs usually lowers insulin levels, which causes the kidneys to release sodium and water (20).
Try to eat a cup of broth, a few olives, or some other salty low carb foods to make up for the lost sodium. Don’t be afraid to add a little extra salt to your meals.
However, if you have congestive heart failure, kidney disease, or high blood pressure, talk to your doctor before increasing the amount of sodium in your diet.
Foods to avoid
These foods are high in carbohydrates and can significantly raise blood sugar levels in people with diabetes:
- bread, pasta, cereal, corn, and other grains
- starchy vegetables, like potatoes, sweet potatoes, yams, and taro
- fruit other than berries
- juice, soda, punch, sweetened tea, etc.
- desserts, baked goods, candy, ice cream, etc.
Stick to low carb foods like meat, fish, eggs, seafood, nonstarchy vegetables, and healthy fats. Avoid foods that are high in carbs.
A sample day of very low carb meals for people with diabetes
Here’s a sample menu with 15 grams or less of digestible carbs per meal. If your personal carb tolerance is higher or lower, you can adjust the serving sizes.
Breakfast: Eggs and spinach
- 3 eggs cooked in butter (1.5 grams of carbs)
- 1 cup sautéed spinach (3 grams of carbs)
You can pair your eggs and spinach with:
- 1 cup blackberries (6 grams of carbs)
- 1 cup coffee with cream and optional sugar-free sweetener
Total digestible carbs: 10.5 grams
Lunch: Cobb salad
- 3 ounces (90 grams) cooked chicken
- 1 ounces (30 grams) Roquefort cheese (1/2 gram of carbs)
- 1 slice bacon
- 1/2 medium avocado (2 grams of carbs)
- 1 cup chopped tomatoes (5 grams of carbs)
- 1 cup shredded lettuce (1 gram of carbs)
- olive oil and vinegar
You can pair your salad with:
- 20 grams (2 small squares) 85% dark chocolate (4 grams of carbs)
- 1 glass of iced tea with optional sugar-free sweetener
Total digestible carbs: 12.5 grams.
Dinner: Salmon with veggies
- 4 ounces grilled salmon
- 1/2 cup sautéed zucchini (3 grams of carbs)
- 1 cup sautéed mushrooms (2 grams of carbs)
To complement your meal and for dessert:
- 4 ounces (120 g) red wine (3 grams of carbs)
- 1/2 cup sliced strawberries with whipped cream
- 1 ounce chopped walnuts (6 grams of carbs)
Total digestible carbs: 14 grams
Total digestible carbs for the day: 37 grams
A meal plan to manage diabetes should space carbs evenly over three meals. Each meal should contain a balance of protein, healthy fats, and a small amount of carbs, mostly from vegetables.
Talk to your doctor before changing your diet
When carbs are restricted, there’s often a dramatic reduction in blood sugar.
For this reason, your doctor will often reduce your insulin and other medication dosages. In some cases, they may eliminate your medication altogether.
One study reported that 17 of 21 study participants with type 2 diabetes were able to stop or reduce their diabetes medication when carbs were limited to 20 grams a day (
In another study, participants with type 1 diabetes consumed less than 90 grams of carbs each day. Their blood glucose improved, and there was less likelihood of low blood sugar because insulin dosages were significantly reduced (
If insulin and other medications aren’t adjusted for a low carb diet, there’s a high risk of dangerously low blood glucose levels, also known as hypoglycemia.
Therefore, it’s important that people who take insulin or other diabetes medications speak with their doctor before starting a low carb diet.
Most people will need to reduce their dosage of insulin or other diabetes medications when following a low carb diet. Not doing so may result in dangerously low blood sugar levels.
Other ways to lower blood sugar levels
In addition to following a low carb diet, physical activity can also help manage diabetes by improving insulin sensitivity.
A combination of resistance training and aerobic exercise is especially beneficial (
One recent observational study found that people with diabetes who slept 6.5 to 7.5 hours per night had better blood glucose management compared to those who slept for less or more time (
Another key to good blood sugar management? Also managing your stress. Yoga, qigong, and meditation have been shown to lower blood sugar and insulin levels (24).
In addition to following a low carb diet, physical activity, quality sleep, and stress management can further improve diabetes care.
The bottom line
Studies show that low carb diets can effectively manage type 1 and type 2 diabetes.
Low carb diets can improve blood sugar management, decrease medication needs, and reduce the risk of diabetic complications.
Just remember to talk to your doctor before making any dietary changes, as your medication dosages may need to be adjusted.