Low-Carb Diets and Diabetes: What to Know

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Last reviewed: October 9, 2026 · Sources: CDC, NIH/NIDDK, American Diabetes Association

Low-carbohydrate eating is one of the most talked-about approaches to managing diabetes. Because carbohydrates have the biggest direct effect on blood glucose, eating fewer of them can lower glucose after meals and, for some people, improve A1C and support weight loss. But low-carb diets are not right for everyone, and they can require medicine changes to stay safe. This guide explains what low-carb eating means, what research shows, potential benefits and risks, and how to do it in a healthy way with your care team.

What counts as "low-carb"?

There is no single definition, but these general ranges are often used:

Moderate or reduced carbohydrate: roughly 26% to 45% of daily calories from carbohydrate.
Low carbohydrate: often described as less than about 26% of calories, or less than about 130 grams of carbohydrate per day.
Very low carbohydrate or ketogenic: often about 20 to 50 grams of carbohydrate per day, low enough that the body produces ketones from fat for fuel.

For comparison, many typical eating patterns include around half of calories from carbohydrate.

What does the research say?

The American Diabetes Association's Standards of Care state that there is no single ideal percentage of calories from carbohydrate, protein, and fat for people with diabetes, and that eating plans should be individualized. The ADA recognizes reducing overall carbohydrate intake as an approach that has shown evidence for improving blood glucose in people with diabetes and that can be applied in a variety of eating patterns. Low-carbohydrate eating plans are listed among several eating patterns that can be appropriate, alongside Mediterranean-style, DASH, and plant-based patterns.

Research findings include:

Low-carb diets can lower A1C and glucose levels, particularly in the short term.
They may help reduce the need for some diabetes medicines.
They can support weight loss, though over longer periods results are often similar to other diets.
Long-term effects and how sustainable very low-carb diets are for most people are still being studied.

Potential benefits

Lower after-meal glucose: Fewer carbs mean smaller rises in glucose after eating.
Reduced medicine needs: Some people need less insulin or fewer medicines, which must be adjusted by a provider.
Weight loss: Many people find that protein and fat help them feel full, which can reduce overall calorie intake. See weight and diabetes.
Lower triglycerides: Some people see improvements in triglycerides and HDL cholesterol.

Potential risks and downsides

Low blood glucose

If you take insulin or medicines that can cause lows, such as sulfonylureas, cutting carbs without adjusting medicines can lead to hypoglycemia. This is the most important safety issue. See hypoglycemia.

Ketoacidosis risk with certain medicines

People taking SGLT2 inhibitors may be at higher risk of a type of ketoacidosis on very low-carbohydrate or ketogenic diets. The ADA advises caution with this combination. People with type 1 diabetes following very low-carb diets also need careful monitoring. See hyperglycemia and DKA.

Nutrient gaps

Cutting out whole grains, fruit, beans, and starchy vegetables can mean less fiber, vitamins, and minerals. Careful planning is needed. See fiber and diabetes.

Heart health

Some low-carb diets are high in saturated fat from red and processed meats, butter, and cheese, which can raise LDL cholesterol in some people. Choosing healthy fats matters. See heart health.

Side effects

When starting a very low-carb diet, some people experience fatigue, headache, constipation, or dizziness for a few days or weeks.

Sustainability

Very restrictive diets can be hard to maintain long term. The best eating plan is one you can keep.

Who should be cautious

Talk with your care team before starting a low-carb diet, especially if you:

Take insulin, sulfonylureas, or SGLT2 inhibitors
Have kidney disease. See kidney health.
Are pregnant, planning pregnancy, or breastfeeding. See diabetes and pregnancy planning.
Have a history of disordered eating
Have high LDL cholesterol or heart disease
Are a child or teen
Are an older adult at risk of malnutrition. See diabetes in older adults.

How to eat lower-carb in a healthy way

Focus on quality

Fill up on nonstarchy vegetables: leafy greens, broccoli, cauliflower, peppers, zucchini, green beans, mushrooms, and tomatoes.
Choose healthy proteins: fish, poultry, eggs, tofu, and legumes in planned portions; limit processed meats.
Choose healthy fats: olive oil, avocado, nuts, and seeds; limit butter and fatty red meat.
Keep some high-fiber carbs: berries, beans, lentils, and small portions of whole grains can fit in many lower-carb plans.
Limit added sugars and refined grains, which add carbohydrate with little nutrition.

Plan meals

Breakfast: eggs with sautéed vegetables, or plain Greek yogurt with berries and nuts.
Lunch: a large salad with grilled chicken or chickpeas, olive oil dressing, and avocado.
Dinner: baked salmon with roasted vegetables and a small portion of quinoa.
Snacks: vegetables with hummus, a handful of nuts, or cheese. See best snacks for diabetes.

Read labels and count carbs

Knowing the carbohydrate content of foods helps you stay within your target. See reading food labels and carb counting.

Monitor closely

Check glucose more often when starting, and share readings with your care team so medicines can be adjusted. See checking blood sugar and CGMs.

Work with a dietitian

A registered dietitian can help you design a lower-carb plan that meets your nutrition needs and preferences.

A moderate approach

You don't need to go to extremes to benefit. Simply cutting back on sugary drinks, sweets, white bread, and large portions of rice and pasta, and replacing them with vegetables and protein, lowers carbohydrate intake meaningfully. The plate method naturally reduces carbohydrate: half the plate nonstarchy vegetables, a quarter protein, a quarter carbohydrate foods, as described by the CDC. See diabetes-friendly eating basics.

Frequently asked questions

Is keto safe for people with diabetes?

It can be for some people with close medical supervision, but it carries risks, especially for those taking insulin, sulfonylureas, or SGLT2 inhibitors. Discuss it with your care team first.

Will I have to eat low-carb forever?

Not necessarily. Many people find a moderate carbohydrate intake they can sustain. The goal is long-term success.

Can I eat fruit on a low-carb diet?

Many low-carb plans include berries and small portions of other fruit. See fruit and diabetes.

Does low-carb mean high-protein?

Not necessarily. Many plans emphasize vegetables and healthy fats with moderate protein. People with kidney disease should ask about protein limits.

How do I know whether low-carb is working for me?

Track your glucose, A1C, weight, cholesterol, and how you feel over several months. Share the results with your care team, who can help you decide whether to continue, adjust, or try another approach.

Do I need to buy special low-carb products?

No. Many packaged low-carb products are expensive and highly processed. Whole foods like vegetables, eggs, fish, beans, nuts, and plain dairy are usually better choices.

Where can I find more reliable information?

Trusted sources include the CDC, NIDDK, MedlinePlus, and the American Diabetes Association. Be cautious with social media posts or products that promise quick fixes, and check new information with your care team before making changes.

Key takeaways

Reducing carbohydrate can lower glucose and may reduce medicine needs and support weight loss.
The ADA recognizes lower-carbohydrate eating as one of several effective approaches; plans should be individualized.
Medicine adjustments are often needed to prevent lows; talk with your care team first.
Focus on vegetables, healthy fats, quality proteins, and fiber-rich carbs.

Sources

Links to the sources cited above appear in the text. We rely on the Centers for Disease Control and Prevention (CDC), the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), and the American Diabetes Association (ADA).

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