Using the Ketogenic Diet to Manage Diabetes

Ask a wide range of experts—healthcare providers, dietitians, and nurses—how they feel about the ketogenic diet for diabetes and you'll probably hear a wide range of answers. Some answers might be based on personal experience, others on scientific evidence about its efficacy, long-term benefits vs. risks, and so on.

Ask people with diabetes who've tried the ketogenic diet about their experience and you'll also hear a wide range of answers. This is because a dietary approach that works for one may not work for someone else.

Ketogenic diets can serve a purpose, but their rigidity and restrictiveness may make them hard to follow and can result in other health issues (such as elevated cholesterol) if not followed properly.

What Is a Ketogenic Diet? 

The typical ketogenic diet restricts carbohydrates to very low amounts and allows for more fat than most other eating plans. The idea is to create a metabolic state called ketosis in which fat is used for energy rather than carbohydrates.

This type of diet plan was developed in the 1920s to treat epilepsy in children and has since been used for a variety of health conditions, Alzheimer's disease, Parkinson's disease, glaucoma, obesity, and diabetes among them. Additionally, athletes have been known to use this plan (or variations of it) to boost performance and lose fat.

Sarah Currie, MS, RD, personal trainer and registered dietitian says, "There is no doubt that the ketogenic diet works for fat loss. And it is medically safe as long as it’s done right. In my experience, people go wrong when they don't ease into this type of eating plan and restrict plant-based vegetables." 

Although there are several variations of the keto diet—for instance, some merely recommend eating 30 grams or fewer carbohydrates per day without specifying how much protein and fat to include—the standard ketogenic diet is more specific. It recommends limiting net carbs to between 25 and 50 grams per day.

For someone following an 1800-calorie diet, this would mean 140 grams of fat, 90 grams of protein, and 45 grams of carbohydrate daily.

Ketosis vs. Ketoacidosis

If you have diabetes and are considering trying a ketogenic diet, it's important to understand the difference between ketosis, a metabolic state in which the body uses fat for fuel, and ketoacidosis, a potentially life-threatening emergency.

In ketosis—the intent of a ketogenic diet—the body turns to fat in the form of ketones as its primary energy source. Ketones are produced by the liver when there is too little glucose in the body to use for fuel.

Ketoacidosis develops when too many ketones build up in the body, causing the blood to become acidic. During ketoacidosis, blood pH decreases and ketones in the blood can exceed 20 mmol/l. This is due to the absence of insulin or too little of it.

When ketoacidosis develops in someone with diabetes, it's called diabetic ketoacidosis (DKA). People with type 1 diabetes are at higher risk of DKA than are those with type 2 diabetes. However, if insulin resistance surges or there is a decrease in the amount of insulin released from the pancreas in someone with type 2 diabetes, DKA can occur and is no less serious.

What the Research Says

There has been some promising research looking at the value of the ketogenic diet as treatment for diabetes.

For example, in one study, all 262 participants were able to eliminate at least one of their diabetes medications, had lower hemoglobin A1C test results, and achieved a 20% reduction in triglycerides after following a ketogenic diet. The diet was based on eating three-to-five servings of vegetables, a moderate amount of protein, and high-quality fat until they were full.

In other research, a meta-analysis of thirteen studies found that individuals assigned to a very low-carb (less than 50 grams per day) ketogenic diet lost weight and experienced a decrease in diastolic blood pressure as compared to those who ate a low-fat diet comprised of less than 30% of calories from fat.

Additionally, those following a ketogenic diet had increased levels of good cholesterol (HDL). But, they also had an increase in LDL (bad cholesterol).

Another meta-analysis found that a low carbohydrate diet had a significant effect on A1C levels and significantly reduced triglycerides concentration (a marker for heart disease). It did not find, however, that a low carbohydrate diet was associated with decreased levels of total cholesterol and LDL cholesterol.

In its Standards of Care in Diabetes guidelines, the American Diabetes Association concludes that low- and very-low-carbohydrate diets, like the ketogenic diet, can improve blood sugar control and reduce the need for diabetes medications. However, it notes that the optimal level of carb restriction and the long-term effects on heart disease risk are still uncertain.

Risks and Considerations

It's important to understand the diet's risks and limitations, and to be ready and willing to take on this type of eating plan.

Among the important things to consider:

• The ketogenic diet can cause hypoglycemia (low blood sugar), especially if medications are not monitored properly.
• If the variation of the ketogenic diet incorporates large amounts of protein, it can put stress on the kidneys. As such, it may not be appropriate for patients with diabetes who have kidney disease.
• Because the diet is restrictive, some people may modify their behaviors (e.g., no longer going out to dinner with friends) and feel socially isolated. It may also cause some to establish an unhealthy relationship with food.

Speak with your healthcare provider about what a ketogenic diet may mean for your health specifically.

Seeking Expert Opinions

If you are thinking about starting the ketogenic diet it is wise not to dive right in for these and other reasons.

"If someone is accustomed to eating 200 or more grams of carbohydrate per day and they suddenly drop down to 50 grams or lower, they are going to feel symptomatic and won't stick with it long enough to use fat as fuel," says Currie.

She adds, "This type of drastic reduction in carbohydrate may work for some people, but can be dangerous for someone who is living with diabetes, particularly if they are not closely managing their blood sugar and medications."

The safest approach to this diet is making sure you are motivated and ready to change and, if so, consulting with a healthcare provider.

If they give you the all-clear to try this way of eating, careful blood glucose monitoring and medication management will be essential. A schedule for that can be established before you begin.

Education and Support

Education and support (both peer and professional) also are important. Registered dietitians and certified diabetes educators can help you approach a ketogenic diet in the most healthy and successful way.

For example, when the diet includes large amounts of saturated fat (e.g., butter, cream, processed meats, full-fat cheese) and doesn't include large amounts of plant-based foods, there can be an increased risk of constipation and elevated LDL cholesterol.

It's important to increase intake of non-starchy vegetables, nuts, seeds, and lean protein, and these professionals can help you choose foods that promote ketosis, protect your cardiovascular health, and keep you full and satisfied.

Cutting out or drastically reducing any type of food could put you at risk for deficiencies that may prompt a need for counseling about food choices and/or supplementation. 

A Word From Verywell

The verdict as to whether or not the ketogenic diet is a viable long-term option for people with diabetes is still out.

If you are interested in it and have your healthcare provider's OK, it might make the most sense to follow this diet temporarily and expand it after you've achieved your goals. People have found success in adding small amounts of good quality carbohydrates back in after a few months.