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How many carbohydrates should diabetes eat?

Finding out how many carbohydrates to eat when suffering from diabetes can seem confusing.

Traditionally, the global dietary guidelines recommend that if you have diabetes, you should get about 45-60% of your calories from carbohydrates every day .

However, more and more experts believe that diabetics should eat less carbohydrates. In fact, many people recommend no more than half of this amount.

This article tells you how much carbohydrates you should eat if you have diabetes.

What is diabetes and pre-diabetes?

Glucose is the main fuel source for human cells.

If you have type 1 or type 2 diabetes, your ability to process and use blood sugar is impaired.

Type 1 diabetes

In type 1 diabetes, the pancreas cannot produce insulin, which is a hormone that allows sugar in the blood to enter the cells. Insulin must be injected instead.

This disease is caused by an autoimmune process, in which the body attacks its insulin-producing cells, called beta cells. Although it is usually diagnosed in children, it can start at any age-even in later adulthood .

Type 2 diabetes

Type 2 diabetes is more common, accounting for about 90% of diagnoses. Like type 1, it can develop in adults and children. However, it is not common in children and usually occurs in people who are overweight or obese.

In this form of disease, your pancreas may not produce enough insulin, or your cells may not be able to resist the effects of insulin. Therefore, too much sugar will stay in your blood.

Over time, as more and more insulin tries to lower blood sugar, your beta cells will degrade. They may also be damaged by high sugar in the blood .

Diabetes can be diagnosed by elevated fasting blood glucose levels or marked glycosylated hemoglobin (HbA1c) levels, which reflects 2-3 months of blood glucose control .


Before the onset of type 2 diabetes, blood sugar levels were elevated, but not enough to be diagnosed as diabetes. This stage is called pre-diabetes.

Pre-diabetes is diagnosed with a blood sugar level of 100–125 mg/dL (5.6–6.9 mmol/L) or a HbA1c level of 5.7–6.4% .

Although not everyone has prediabetes, it is estimated that about 70% of people will eventually develop type 2 diabetes .

More importantly, even if pre-diabetes never develops into diabetes, people with this disease are still at higher risk of heart disease, kidney disease and other complications related to high blood sugar .


Type 1 diabetes is caused by the destruction of pancreatic beta cells, while type 2 diabetes is caused by insufficient insulin or insulin resistance. Pre-diabetes often develop into diabetes.

Many factors including exercise, stress, and disease can affect your blood sugar levels.

One of the biggest factors is diet.

Among the three nutrients of carbohydrates, protein and fat, carbohydrates have the greatest impact on blood sugar. That's because your body breaks down carbohydrates into sugar, which enters the bloodstream.

This happens with all carbohydrates, from refined foods such as potato chips and biscuits to healthy foods such as fruits and vegetables.

However, all natural foods contain fiber. Unlike starch and sugar, naturally occurring fiber does not increase blood sugar levels and may even slow this rise.

When diabetics eat foods high in effective carbohydrates, their blood sugar levels will rise sharply. High carbohydrate intake usually requires high doses of insulin or diabetes medications to control blood sugar.

Given their inability to produce insulin, people with type 1 diabetes need to inject insulin multiple times a day, no matter what they eat. However, eating less carbohydrates can significantly reduce the insulin dose at mealtimes.


Your body breaks down carbohydrates into sugar, which enters the bloodstream. Diabetes patients with a lot of carbohydrates need insulin or drugs to prevent blood sugar from rising too much.

Diabetes carbohydrate restriction

Many studies support the use of carbohydrate restriction in diabetic patients.

Low carbohydrate, ketogenic diet

Diets that are very low in carbohydrates usually cause mild to moderate ketosis , a condition where your body uses ketones and fats instead of sugar as the main energy source.

Ketosis usually occurs when the daily intake of total carbohydrates or digestible carbohydrates (total carbohydrates minus fiber) is less than 50 or 30 grams. This is equivalent to no more than 10% of calories in a 2000 calorie diet.

Before the discovery of insulin in 1921, diabetic patients had formulated a low-carbohydrate, ketogenic diet .

Many studies have shown that limiting carbohydrate intake to 20 to 50 grams per day can significantly reduce blood sugar levels in diabetic patients, promote weight loss and improve heart health .

In addition, these improvements usually come quickly.

For example, in a study of obese and diabetic patients, limiting carbohydrates to 21 grams per day for 2 weeks resulted in a spontaneous decrease in calorie intake, a decrease in blood sugar levels, and a 75% increase in insulin sensitivity .

In a small 3-month study, people ate a calorie-restricted low-fat diet or low-carbohydrate diet, with a maximum intake of 50 grams of carbohydrates per day.

The low-carbohydrate group had an average decrease of 0.6% in HbA1c, and the weight loss was twice that of the low-fat group. Moreover, 44% of them stopped at least one diabetes drug, compared with 11% in the low-fat group .

In fact, in some studies, insulin and other diabetes medications have been reduced or stopped due to improved blood sugar control .

A diet containing 20-50 grams of carbohydrates has also been shown to lower blood sugar levels and reduce the risk of disease in patients with prediabetes .

In a small 12-week study, men with obesity and prediabetes received only 30 grams of carbohydrates per day on a Mediterranean diet. Their fasting blood glucose dropped to an average of 90 mg/dL (5 mmol/L), which was well within the normal range .

In addition, these men lost an astonishing 32 pounds (14.5 kg) on ​​average, and had significant reductions in triglycerides, cholesterol, and blood pressure, among other benefits .

Importantly, these men no longer meet the criteria for metabolic syndrome due to lower blood sugar, weight, and other health indicators.

Although there are concerns that high protein intake in a low-carbohydrate diet may cause kidney problems, a recent 12-month study found that very low carbohydrate intake does not increase the risk of kidney disease .

Low carbohydrate diet

Many low-carbohydrate diets limit carbohydrates to 50-100 grams per day, or 10-20% of calories.

Although there are few studies on carbohydrate restriction in patients with type 1 diabetes, existing studies have reported impressive results .

In a long-term study of patients with type 1 diabetes who restricted carbohydrates to 70 grams per day, participants saw an average decrease in their HbA1c by 7.7% to 6.4%. Moreover, their HbA1c levels remained unchanged after 4 years .

The 1.3% reduction in HbA1c is a significant change for several years, especially for patients with type 1 diabetes.

One of the biggest concerns for people with type 1 diabetes is hypoglycemia , where blood sugar drops to dangerously low levels.

In a 12-month study, adults with type 1 diabetes who restricted their daily carbohydrate intake to less than 90 grams had 82% fewer episodes of hypoglycemia than they did before eating .

People with type 2 diabetes can also benefit by limiting their daily carbohydrate intake .

In a small 5-week study, men with type 2 diabetes who consumed a high-protein, high-fiber diet in which 20% of calories came from carbohydrates reduced their fasting blood glucose by 29% on average .

A moderate carbohydrate diet

A more moderate carbohydrate diet can provide 100–150 grams of digestible carbohydrates per day, or 20–35% of calories.

Some studies on this type of diet report that it has good results in diabetic patients .

In a 12-month study of 259 patients with type 2 diabetes, those who followed the Mediterranean diet ( 35% or less calories from carbohydrates) had a significant reduction in HbA1c on average-from 8.3% to 6.3% .

Find the right range

Studies have confirmed that a variety of restrictions on carbohydrate intake can effectively reduce blood sugar levels .

Since carbohydrates increase blood sugar, reducing it to any degree can help control blood sugar levels.

For example, if you currently consume about 250 grams of carbohydrates per day, reducing your intake to 150 grams can greatly reduce blood sugar after meals.

In other words, strictly limiting the intake of 20 to 50 grams of carbohydrates per day seems to have the most significant effect, and can even reduce or even eliminate the need for insulin or diabetes drugs.


Studies have shown that restricting carbohydrates can benefit diabetics. The less carbohydrate intake, the greater the impact on blood sugar levels and other health indicators.

Many delicious, nutritious, low-carbohydrate foods will only raise blood sugar levels very little. These foods can be consumed in moderation in a low-carbohydrate diet.

However, you should avoid the following high-carbohydrate foods:

  • Breads, muffins, rolls and bagels
  • Pasta, rice, corn and other grains
  • Potatoes, sweet potatoes, yam and taro
  • Milk and sweet yogurt
  • Most fruits, except berries
  • Cakes, cookies, pies, ice cream and other desserts
  • Snacks such as pretzels, french fries and popcorn
  • Fruit juice, soda water, sweetened ice tea and other sweetened beverages
  • beer

Remember, not all of these foods are unhealthy. For example, fruits may be nutritious. However, they are not the best choice for people trying to control blood sugar levels by reducing carbohydrate intake.


In a low-carbohydrate diet, beer, bread, potatoes, fruits and sweets should be avoided.

Is a low-carb diet always best for diabetes?

Low-carbohydrate diets have been proven to lower blood sugar and improve other health indicators in diabetic patients.

At the same time, certain high-carbohydrate diets are also believed to have similar effects.

For example, some studies have shown that a low-fat vegan or vegetarian diet can improve blood sugar control and overall health .

In a 12-week study, a daily vegan diet based on brown rice contained 268 grams of carbohydrates (72% of calories) than the total daily carbohydrates in a standard diabetic diet of 249 grams (accounting for 64% of calories) reduced the participants’ HbA1c levels. Calories) .

The analysis of 4 studies found that people with type 2 diabetes following a low-fat natural longevity diet consisting of 70% carbohydrates can significantly reduce blood sugar and other health indicators .

The Mediterranean diet can also improve blood sugar control and provide other health benefits for diabetics .

However, it must be noted that these diets are not directly compared with low-carbohydrate diets, but with standard low-fat diets often used for diabetes management .

In addition, more research on these diets is needed.


Studies have shown that certain high-carbohydrate diets may help in the treatment of diabetes. Still need to study.

How to determine the optimal carbohydrate intake

Although studies have shown that many different levels of carbohydrate intake may help control blood sugar, the optimal amount varies from person to person.

The American Diabetes Association (ADA) once recommended that diabetics get about 45% of calories from carbohydrates.

However, ADA now advocates a personalized approach in which the ideal carbohydrate intake should take into account your dietary preferences and metabolic goals .

It is important to eat some carbohydrates that are most felt and can be maintained for a long time.

Therefore, determining how many carbohydrates to eat requires some testing and evaluation to find out which carbohydrate is best for you.

To determine your ideal carbohydrate intake, use a blood glucose meter to measure blood sugar before and 1-2 hours after a meal.

To prevent damage to blood vessels and nerves, the highest level your blood sugar should reach is 139 mg/dL (8 mmol/L).

However, you may want to drop to an even lower level.

In order to reach your blood sugar goal, you may need to limit your carbohydrate intake to less than 10, 15 or 25 grams per meal.

In addition, you may find that blood sugar rises more at certain times of the day, so the upper carbohydrate limit for dinner may be lower than that for breakfast or lunch.

Generally, the fewer carbohydrates you consume, the smaller your blood sugar rises, and the fewer diabetes medications or insulin you need to stay within a healthy range.

If you are taking insulin or diabetes medications, it is important to talk to your healthcare provider before reducing your carbohydrate intake to ensure the proper dosage.


To determine the optimal carbohydrate intake for diabetes management, you need to test your blood sugar and make necessary adjustments based on your response (including how you feel).

Bottom line

If you have diabetes, reducing your carbohydrate intake may be beneficial.

A number of studies have shown that daily intake of 20-150 grams of carbohydrates or 5-35% of calories can not only improve blood sugar control, but also promote weight loss and other health improvements.

However, some people can hold more carbohydrates than others.

Testing your blood sugar and paying attention to how you feel under different carbohydrate intake can help you find the best range of diabetes control, energy levels and quality of life.


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