A Guide to Low Carb Diets for Diabetes

Diabetes is a chronic medical condition characterized by elevated blood sugar levels. This elevated glucose occurs due to either insufficient insulin production (as in type 1 diabetes) or the body's resistance to insulin (or type 2 diabetes).

A low-carb diabetes diet is a nutritional approach specifically designed to manage blood sugar levels in people living with diabetes. This type of diet plan focuses on minimizing the consumption of carbohydrates, which are known to rapidly raise blood sugar levels, while emphasizing the intake of foods that help stabilize glucose levels.

This article explains how carbs affect diabetes, the ideal carbohydrate intake for people with diabetes, how carbohydrates raise blood sugar levels, and the risks and considerations for those on a low-carb diabetes diet.

How Do Carbs Affect Diabetes?

Carbohydrates play a significant role in affecting diabetes because they directly impact blood sugar levels.

When you eat or drink carbohydrates, your body breaks them down into glucose, which enters the bloodstream, causing an increase in blood sugar levels. For individuals with diabetes, this process can be problematic due to issues with insulin, a hormone responsible for regulating blood sugar.

Type 1 Diabetes

In type 1 diabetes, the immune system mistakenly destroys the insulin-producing cells in the pancreas. Therefore, the body can no longer produce insulin.

When carbohydrates are consumed, blood sugar levels can rise uncontrollably without the hormone insulin to facilitate glucose uptake into cells. To manage type 1 diabetes, daily insulin injections are essential for survival.

This type usually occurs in kids and young adults, although people can acquire type 1 diabetes at any age.

Type 2 Diabetes

In type 2 diabetes, the body either produces insufficient insulin or fails to use it effectively, causing an excess of glucose to accumulate in the bloodstream. This is the most common form of diabetes, and it usually occurs in middle-aged or older people; however, it can sometimes occur in children.

Excessive carbohydrate intake in type 2 diabetes can overwhelm the limited insulin response, leading to elevated blood sugar levels.

Uncontrolled Diabetes Long-Term Complications

Managing carbohydrate intake is crucial for individuals with diabetes to help maintain stable blood sugar levels and prevent complications.

Potential complications of uncontrolled diabetes may include:

• Eye problems
• Difficulty controlling blood pressure and cholesterol
• Nerve damage
• Digestive problems
• Kidney damage
• Immune system weakness
• Depression
• Increased risk of dementia
• Irregular menstrual periods and difficulty getting pregnant

Low-carb diets may control these fluctuations and improve diabetes management.

Can Very-Low-Carb Diets Help Manage Diabetes?

A very-low-carb diet for diabetes, also known as a very-low-carbohydrate ketogenic diet (VLCKD), is an eating plan that significantly restricts carbohydrate intake to help manage blood sugar levels. In this diet, carbohydrates typically make up only a small percentage of daily caloric intake, with the majority of calories coming from fats and a moderate amount of them coming from protein.

This type of diet involves restricting daily carbohydrate intake to a range of 20–50 grams, which is less than 26% of a typical 2,000-calorie daily diet.

The primary objective is to trigger a metabolic process called ketosis, by which the body switches from burning carbs to burning fat for energy. Most of these diets don't emphasize calorie counting; instead, they rely on higher proportions of protein and fat, which are thought to promote a feeling of fullness.

Impacts of Low-Carb Diets on Type 1 Diabetes

One 2018 systematic review of nine research studies evaluated the effects of low carbohydrate diets on glycemic control of adults and children with type 1 diabetes. Here is what the review found:

Improved Blood Sugar Control

Some of the studies in the review showed that following a low-carb diet can help reduce A1C, which indicates better blood sugar control. This is important because stable blood sugar levels can reduce the risk of diabetes-related complications.

Reduced Insulin Needs

Several studies also suggested that following a low-carb diet may lead to a decrease in insulin doses, which can be beneficial in preventing issues like low blood sugar, weight gain, and metabolic problems.

Impacts of Low-Carb Diets on Type 2 Diabetes

There is also evidence that low-carbohydrate and very-low-carbohydrate diets help people with type 2 diabetes better manage their glucose levels.

Short-Term Glycemic Control (8 Weeks or less):

One 2005 study involving 10 people with obesity and type 2 diabetes found that when they followed a low-carb Atkins-style diet for two weeks, their fasting blood sugar levels improved significantly. In addition, insulin levels in the blood also decreased, and the patients became more sensitive to insulin.

A 2017 study found that people with type 1 diabetes on a low-carb diet had longer periods of time with normal blood sugar, less time with low blood sugar, and less glucose variability.

In addition, the average A1C, a measure of blood sugar control, went down from 7.3% to 6.8% in just 14 days.

Intermediate-Term Glycemic Control (3–6 Months):

Another study involved patients with type 2 diabetes who followed a diet with less than 20 grams of carbohydrates per day for 16 weeks. Researchers also saw a 17% reduction in fasting blood sugar levels and a drop in A1C from 7.5% to 6.3%.

What Is the Ideal Carb Intake for People With Diabetes?

The ideal carbohydrate intake for people with diabetes can vary depending on individual factors such as:

• Age
• Activity level
• Type of diabetes
• Medications
• Overall health goals

Low-carbohydrate diets may call for 120–225 total carbohydrates per day, and very-low-carbohydrate diets may call for as little as 20–50 carbohydrates per day.

Working with your healthcare provider or registered dietitian to determine the most appropriate carbohydrate intake for your specific needs is essential. They can help tailor a plan that suits your health goals and medical condition.

Carb Recommendations for People With Diabetes

Food carbohydrates can be categorized into three primary types: starches, sugars, and fiber.

The term "total carbohydrate," as nutrition labels indicate, includes all these categories. The aim is to opt for nutrient-dense carbohydrates, which are high in vitamins, minerals, and fiber. In addition, it is important to prioritize carbohydrates low in added sugars, sodium, and unhealthy fats.

The American Diabetes Association (ADA) recommends that people with diabetes prioritize the following:

Non-Starchy Vegetables

Non-starchy vegetables in their whole, unprocessed form, such as:

• Cucumbers
• Broccoli
• Lettuce
• Green beans
• Tomatoes

These vegetables are fiber-rich and have minimal carbohydrates, resulting in a limited impact on blood sugar levels. According to the ADA's Diabetes Plate Method, vegetables should constitute half of what's on your plate.

Whole, Minimally Processed Carbohydrates

Whole carbohydrate sources include fruits such as:

• Apples
• Blueberries
• Strawberries
• Cantaloupe

Fiber-Rich Whole Grains

Fiber-rich whole grains include:

• Brown rice, quinoa, or bulgur
• Whole wheat bread and pasta
• Oatmeal or steel-cut oats
• Corn
• Green peas
• Sweet potatoes
• Legumes such as lentils, black beans, kidney beans, or garbanzo beans

In the context of the Diabetes Plate Method, foods from this category should comprise about a quarter of what's on your plate.

Limit your consumption of refined, highly processed carbohydrate foods and those containing added sugars. Items to avoid include:

• Soda
• Sweet tea
• Fruit juices
• White bread
• White rice
• Sugary cereals
• Candy
• Chips
• Cake and other sweet treats

Which Carbs Raise Blood Sugar Levels?

All carbohydrates raise blood sugar levels, but not all carbs have the same effect. The impact on blood sugar largely depends on the type of carbohydrates and how quickly they are absorbed.

The glycemic index (GI) is a numerical scale that ranks carbohydrates in foods based on how quickly and how much they raise blood sugar levels when consumed. Carbohydrate-containing foods are assigned a GI value, typically ranging from 0 to 100, with higher values indicating a faster and more significant increase in blood sugar.

Here's what the GI values generally represent:

Low GI (55 or less): These foods cause a slower and more gradual increase in blood sugar levels. They are often recommended for people with diabetes or those who are looking to manage their blood sugar.

Here are examples of low-GI foods:

• Apples, oranges, grapefruit
• Oatmeal, steel-cut or rolled
• High-fiber bran cereal
• Quinoa
• Milk and yogurt
• Pasta, parboiled (converted) rice
• Most nuts, legumes, and beans
• Carrots, non-starchy vegetables, greens
• Bulgur, barley
  

Medium GI (56–69): Foods with moderate GI values cause a somewhat faster increase in blood sugar.

Examples of medium GI foods include:

• Raisins
• Brown rice
• Rye or pita bread
• Couscous
  

High GI (70 or more): These foods result in a rapid and substantial spike in blood sugar levels when consumed.

Examples of high-GI foods include:

• White bread
• Bagels
• White rice
• Honey
• Watermelon
• Pineapple
• Potatoes
• Most processed cereals, instant oatmeal
• Most snack foods

It's important for individuals with diabetes or those looking to manage their blood sugar levels to monitor their carbohydrate intake and choose complex carbohydrates with a lower glycemic index. These foods are absorbed more slowly, leading to more gradual increases in blood sugar levels and better overall blood sugar control.

Risks and Considerations

There are also some risks and considerations associated with low-carb diets for people with diabetes:

Hypoglycemia (Low Blood Sugar)

One of the immediate risks of a low-carb diet for people with diabetes is the potential for hypoglycemia, or low blood sugar. Drastically reducing your carbohydrate intake can lead to a rapid drop in blood sugar levels, especially if you take medications that lower blood sugar.

Hypoglycemia can cause symptoms like dizziness, confusion, sweating, and even loss of consciousness in severe cases.

Nutrient Deficiencies

A low-carb diet, if not well balanced, can potentially lead to nutrient deficiencies.

Carbohydrates are a primary source of fiber, vitamins, and minerals in many people's diets. Cutting them out or severely restricting them may result in inadequate intake of essential nutrients, such as fiber, potassium, and certain B vitamins. To mitigate this risk, it's crucial to carefully plan a low-carb diet to include a variety of nutrient-dense foods like vegetables, nuts, seeds, and lean proteins.

Summary

Carbohydrates play a significant role in affecting diabetes because they directly impact blood sugar levels. Research shows that low-carbohydrate diets may help people with diabetes reduce their glucose levels, lose weight, and decrease the long-term health risks of diabetes over time.

Remember, your ideal carb intake varies based on factors like age, activity level, and health goals, so always consult your healthcare provider or dietitian for the best personalized plan for managing your diabetes.