Keto Diet For Type 2 Diabetes: Pros, Cons, And Official Recommendations

If you have type 2 diabetes, you need to be careful about what you eat. When trying a new diet, you need to know how it affects your condition.

Keto (short for ketogenic) diet is a low-carb and high-fat eating plan which people adopt for many purposes, including weight loss. Research¹ suggests that it may also improve insulin sensitivity in some people with diabetes. This means your body's ability to respond to insulin may get better.

Let's take a closer look at the effects of the keto diet on type 2 diabetes. 

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What is the keto diet?

In 1921, doctors used the keto diet to treat epilepsy in children. When scientists developed antiepileptic medication, this diet's popularity waned quickly. Recently, it re-emerged as a weight-loss tool.

A ketogenic diet changes the way your body makes energy. A regular eating pattern involves carbohydrate consumption. When your body notices the increased availability of carbohydrates,  it turns them into glucose to use as a source of energy.

If you remove most carbohydrates from your diet, your body breaks down stored fats to use them as a source of energy. When breaking down fats, your body produces ketones to generate energy, causing the body to enter a metabolic state called ketosis. 

At rest and during light to moderate-intensity exercise, your body predominantly uses fat rather than glucose as an energy source. So the keto diet simply boosts your body’s fat use.

The general recommendations for macronutrient (macros) distribution for a keto diet are:

  • Fat: 55%-60 %

  • Protein: 30%-35%

  • Carbohydrates: 5%-10%

In a 2,000-calorie daily diet, you get around 20-50g of carbohydrates.

Overall, ketosis is a natural energy-producing process that your body initiates when faced with a lack of carbohydrates. While this diet may be beneficial for some people, it may not be a healthy choice for others.

If you choose the keto diet for weight loss, you can't expect to immediately get rid of extra fat. You usually lose the first several pounds quickly because your body burns stored carbohydrates, pushing out body water. After that, the weight loss process is generally the same as with conventional weight-loss diets.

Potential advantages of the keto diet are:

  • Weight loss

  • Improved acne

  • Reduction of certain cancer risks

  • Possible heart health improvements

  • Possible protection for brain function

  • Possible reduction of seizures in people with epilepsy

  • Improved PCOS (Polycystic ovary syndrome) symptoms

However, the diet can also have certain downsides, including:

After starting a keto diet, you may experience unpleasant symptoms such as headaches, vomiting, constipation, mood swings, and more. This is colloquially known as “keto flu.”

One of the most severe problems you could face by minimizing carbohydrates in your diet is nutrient deficiency. You need to speak with your doctor and a dietician to find keto-friendly replacements for vital vitamins and nutrients. 

Is keto good for type 2 diabetes?

Since the keto diet reduces carbohydrate intake and keeps your body from receiving glucose, you may think it’s ideal for type 2 diabetes. Here is how the keto diet affects your blood sugar levels.

Carbohydrates are the main source of glucose for your body, so removing them from your diet will reduce blood sugar spikes after meals.

However, it's worth noting that ADA (American Diabetes Association) doesn't recommend the ketogenic diet over other diets for people with diabetes.

The benefits of the keto diet for people with type 2 diabetes are:

Weight loss

Obesity is a major risk factor for insulin resistance. Losing above 10% of your body weight or 15kg could put your type 2 diabetes into remission.

Lower hemoglobin A1C levels

Reducing carbohydrate intake lowers glucose levels, reducing the number of hemoglobin proteins covered with sugar. This can help you achieve the A1C goal of 7% or less.

Lower triglycerides

Studies² show that a long-term keto diet reduces the number of triglycerides in people with obesity. High levels of triglycerides are an independent risk factor for diabetes.

When following a keto diet, you may need adjustments to your diabetes medication: Better glycemic control decreases the need for extra insulin. 

Keto diet vs. conventional diets 

Maintaining a healthy weight and watching what you eat are the main recommendations for type 2 diabetes. That's why many patients adopt low-calorie diets. Could the ketogenic diet offer better results than conventional low-calorie diets? Some studies say that they can. It is important to emphasize that the keto diet is a low-calorie diet most of the time. Like any other hypercaloric diet, a high-calorie keto diet can lead to weight gain and other negative outcomes. 

A study³ with 28 overweight participants with type 2 diabetes demonstrated that the keto diet could improve glycemic control to a point where diabetes drugs were discontinued or reduced.

Another study⁴ with 83 people showed that the keto diet might be useful for the short-term management of insulin resistance.

A study⁵ with 132 obese adults with diabetes revealed that a low-carb diet was more favorable than a conventional diet. Although both groups had similar weight loss results, the effects on glycemic control were better for those on the low-carb diet.

Another 2012 study⁶ observed 163 overweight and obese adults. They had an opportunity to choose a low-calorie diet or a keto diet.

After 24 weeks, researchers found that both diets had a beneficial effect on the subjects. However, the benefits were more noticeable in the keto group. The diet appeared to improve glycemic control.

A 2003 study⁷ assigned 63 obese men and women to either a low-carbohydrate, high-fat, and high-protein diet or a low-calorie, high-carbohydrate, and low-fat diet.

The results showed the low-carbohydrate diet was more effective for weight loss within six months. However, after one year, the differences weren't substantial. Additionally, a low-carbohydrate diet improved risk factors for coronary heart disease.

Another study⁸ compared the effects of a low-fat diet to a low-carbohydrate diet in people with diabetes. The experiment demonstrated that HbA1c levels in the low-carb group decreased significantly compared to the low-fat group.

Overall, this study concluded that a low-carb diet could improve blood glucose levels better than a low-fat diet.

Finally, another study⁹ evaluated the keto diet's short-term (four months) safety and tolerability vs. conventional weight loss programs. The results suggested that weight loss and reduction in waist circumference were more substantial in people on the keto diet. People with type 2 diabetes following the keto diet experienced a decline in HbA1c and improved glycemic control.

The key points of the comparison are:

  • Any diet, whatever it is, will result in weight loss if it is a low-calorie diet.

  • Several studies show that low-carbohydrate and high-fat diets promote weight loss, healthier blood glucose levels, and insulin production.

  • Studies also demonstrate that low-carb and high-fat diets can have side effects, such as higher LDL cholesterol.

  • There isn't enough data¹⁰ to support the long-term safety, health benefits, and efficacy of a ketogenic diet for people with type 2 diabetes. That's why you need to speak to your doctor before going on a keto diet.

  • If you have type 2 diabetes, you will benefit from restricting rapidly digestible carbs, such as sugar, white rice, and potatoes. If you choose the keto diet, avoid saturated fats. Instead, focus on unsaturated fatty acids.

  • Since there aren't any robust long-term studies that can support the keto diet as a preventive measure for type 2 diabetes, experts don't officially recommend this diet for prevention yet. The combination of long-term low carb and high-fat consumption warrants further studies.

Overall, it may seem that the keto diet can be more beneficial for people with type 2 diabetes than the traditional low-calorie diet. However, since both benefits and side effects require further research, it's ill-advised to try the keto diet without your doctor's close supervision.

What do experts say?

In the past, when insulin medication wasn't available, doctors used to recommend a low-carbohydrate diet to patients with diabetes. The macronutrient distribution of these low-carb diets was less strict than in the keto diet and didn't always initiate ketosis.

Experts from the World Health Organization, the German Food Council, and the British Scientific Advisory Committee of Nutrition believe the best approach includes the following:

  • A diet with lots of cereals, fruits, veggies, and legumes

  • Moderate fat intake

  • Moderate sugar intake

  • Whole-wheat products over low-fiber starchy foods

  • Daily physical exercise

With this guidance, you can maintain a healthy weight and prevent chronic lifestyle diseases. International experts recommend a relatively high carbohydrate intake, which goes against the ketogenic diet.

Health authorities in the United States don't recommend the keto diet to people with diabetes. When it comes to diets, they recommend:

More studies are needed for the keto diet to be an international recommendation. 

Should you try the keto diet for type 2 diabetes? 

If you want to try the keto diet, your doctor and dietician will need to supervise you closely. Ask your doctor for their medical opinion. If you aren't controlling your diabetes with insulin medication, your doctor is more likely to suggest trying the diet.

If you’re taking insulin medication, you need closer supervision since you may be at risk of hypoglycemia (low blood sugar levels) while on the keto diet.

It's important to remember that the first weeks of the keto diet often come with various unpleasant side effects, including excessive thirst, fatigue, and frequent urination that you may mistake for hyperglycemia symptoms.

If your doctor approves of you trying the keto diet, it's crucial to monitor your symptoms closely. Keep in mind that there are always alternatives to the keto diet.

Other diets for people with type 2 diabetes

Besides a conventional low-calorie diet that helps with weight loss, people with type 2 diabetes can consider other eating plans.

Atkins diet 

As a ketogenic diet, the Atkins diet focuses on reducing carbohydrate intake. Designed by Dr. Robert Atkins, this diet has several phases that you need to follow in a specific order.

The induction phase begins with restricting carbohydrate intake to 20g a day. The following stages gradually add carbohydrate-containing foods into the plan. The final step focuses on maintaining the results achieved by the previous phases.

In 2003, John Hopkins Hospital developed a Modified Atkins Diet (MOD) that involved a less restrictive dietary treatment. This diet has the following macronutrient distribution:

  • Fat: 50 %

  • Carbohydrates and protein: 50%

The biggest difference between the keto and Atkins diets is the lack of restriction on proteins. As a keto diet, people who follow MOD enter the state of ketosis and start using stored fat for energy.

The overall effect of the modified Atkins diet is the same for people with diabetes as with the ketogenic diet. More studies need to confirm the positive impact of the modified Atkins diet on people with type 2 diabetes.

Paleo diet 

The Paleo diet is an eating plan which focuses on supposed foods early humans may have eaten in the Paleolithic era. During this period, people were only eating whatever they could hunt or gather. This includes fish, meat, fruits, veggies, nuts, and seeds.

By cutting out grains and legumes, people who follow the Paleo diet are removing the majority of carbohydrates from their meals. This diet includes low carbs, high protein, and moderate or high fat. The macronutrient distribution is usually:

  • Fat: 50 %

  • Protein: 30%

  • Carbohydrates: 20%

Several studies and trials have demonstrated the benefits of the Paleo diet for type 2 diabetes. They showed that compared to the conventional diabetes diet, the Paleo diet improved blood sugar control, lipid profiles, insulin sensitivity, and several cardiovascular risk factors.

The lack of substantial long-term studies keeps the Paleo diet out of official recommendations for patients with type 2 diabetes. If you decide to try this diet, consult your doctor first.

South Beach diet

The South Beach diet focuses on low carbs, high proteins, and moderate fats. There is also a ketogenic version of the South Beach diet.  

The traditional South Beach diet has three phases:

  1. The first phase lasts two weeks and restricts almost all carbohydrates. You eat lean protein, high-fiber veggies, and foods with unsaturated fat.

  2. The second phase usually lasts until you reach your dieting goals. You can add good carbohydrates and focus on high protein intake (around 25% of daily calories).

  3. The third phase is the maintenance phase which allows you to eat all foods in moderation.

Since research¹¹ shows that low-carb diets may be beneficial for people with type 2 diabetes, the South Beach diet could be a good way to lose weight and control blood sugar levels. However, you still need to speak to your doctor before trying it.

How to follow a keto diet

If your doctor approved a keto diet for your type 2 diabetes, start by studying the foods you can and can't eat.

Foods you can't eat on a keto diet:

  • Grains: Rice, corn, cereal, pasta, and other wheat-based food

  • Sugar: Honey, syrups, agave, juice, candy, and anything else high in sugar

  • Legumes: Peas, lentils, chickpeas, beans

  • Tubers: Potatoes, yams

  • Root veggies: Carrots, beets, radishes, turnips

  • Saturated fats: Mayonnaise, processed vegetable oils, sausages, hard cheeses, butter

  • Fruits: Except limes, lemons, tomatoes, and berries

Foods you can eat on a keto diet:

  • For carbohydrates: Broccoli, eggplants, bell peppers, celery, asparagus

  • For fats: Olive oil, avocado oil, flaxseeds, pumpkin seeds, nuts, coconuts, high-fat dairy, high-fat salad dressing, avocados

  • For protein: Chicken and turkey (dark meat), beef, salmon, tuna, shrimp, pork, cheese, eggs

You can replace sugar with low-carb sweeteners, such as Stevia and erythritol. It may be hard to understand what your meals should look like on a ketogenic diet. You may want to consider speaking with a dietician and designing a meal plan for at least a week.  

Preparing for side effects 

When your body enters ketosis (this can happen within 48 hours), you can start experiencing unpleasant side effects, including headaches, muscle spasms, excessive thirst, fatigue, and insomnia. For many people, these side effects go away after a few weeks.

If ketosis hinders your quality of life significantly, speak to your doctor about an alternative eating plan.

Cooking at home vs. eating out 

Following a keto diet usually involves a substantial amount of cooking. Cooking at home keeps your meal plan under control. Eating out can become a challenge for people on the keto diet as you can’t know the exact number of carbs, proteins, and fats in a restaurant-cooked meal.

Starting a keto diet with insulin-treated type 2 diabetes 

If you take insulin to control your diabetes, your doctor may recommend lowering the dosage when you begin the keto diet. The initial dosage reduction for people with diabetes who go on a low-carb diet is usually 30%-50%.

With time, your doctor may lower the dosage even further. This requires continuous diligent monitoring of your blood sugar levels. Some patients may come off insulin completely.

The lowdown 

Many studies have shown that the keto diet can benefit people with type 2 diabetes. It can improve glycemic control and help you lose weight. However, the long-term effects of the keto diet on type 2 diabetes are still unknown.

That's why this type of diet isn't part of the official recommendations for diabetes management. A low-calorie diet that isn’t as carbohydrate restrictive is the general recommendation.

If you decide to try the ketogenic diet, speak to your doctor about your plans. They can give recommendations based on your symptoms, condition, and medical history.

  1. Low-carb and ketogenic diets in type 1 and type 2 diabetes (2019)

  2. Long-term effects of a ketogenic diet in obese patients (2004)

  3. A low-carbohydrate, ketogenic diet to treat type 2 diabetes (2005)

  4. Comparison of isocaloric very low carbohydrate/high saturated fat and high carbohydrate/low saturated fat diets on body composition and cardiovascular risk (2006)

  5. The effects of low-carbohydrate versus conventional weight loss diets in severely obese adults: One-year follow-up of a randomized trial (2004)

  6. Effect of low-calorie versus low-carbohydrate ketogenic diet in type 2 diabetes (2012)

  7. A randomized trial of a low-carbohydrate diet for obesity (2003)

  8. The effect of low-carbohydrate diet on glycemic control in patients with type 2 diabetes mellitus (2018)

  9. Short-term safety, tolerability and efficacy of a very low-calorie-ketogenic diet interventional weight loss program versus hypocaloric diet in patients with type 2 diabetes mellitus (2016)

  10. Overweight and diabetes prevention: Is a low-carbohydrate–high-fat diet recommendable? (2018)

  11. Low carbohydrate diet | StatPearls

Other sources:

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