The ketogenic, or keto, diet is a very-low-carb, high-fat diet that has been shown to offer several health benefits.

In recent years, interest in using the keto diet as a tool to help manage diseases, such as epilepsy, cancer, and diabetes, has increased.

Type 1 diabetes mellitus is a chronic condition in which your pancreas produces little or no insulin.

It should not be confused with type 2 diabetes, which affects the way your body processes blood sugar and is usually associated with insulin resistance.

Though the keto diet has been shown to improve blood sugar control and reduce insulin requirements, several complications may arise for those with type 1 diabetes (1).

This article tells you whether the keto diet is safe for those with type 1 diabetes.

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A common area of misunderstanding surrounding the keto diet is the concept of diabetic ketoacidosis (DKA) versus nutritional ketosis (ketosis).

Knowing the difference between the two becomes even more important if you have type 1 diabetes.

On a keto diet, you significantly reduce your carb intake to less than 50 grams per day and increase your fat intake instead.

This pushes your body to produce ketones from fat in your liver and use fat as its main fuel source as opposed to carbs.

This shift in metabolism results in nutritional ketosis, which means your body uses ketones in your blood for energy.

On the other hand, diabetic ketoacidosis is a medical emergency that occurs mostly in people with type 1 diabetes if they don’t take insulin.

Without insulin to transport blood sugar into your body’s cells, blood sugar and ketone levels rise rapidly, disrupting your blood’s acid-base balance (2).

Thus, the main difference between nutritional ketosis and diabetic ketoacidosis is as follows:

  • In ketosis, only ketone levels are elevated, allowing your body to use mostly fat for energy.
  • In diabetic ketoacidosis, blood sugar and ketone levels are very high, resulting in a critical health state.

If you have type 1 diabetes and are thinking about trying a ketogenic diet, it’s extremely important to work with healthcare professionals, such as a registered dietitian and medical doctor, to avoid serious complications.

Summary Nutritional ketosis is a metabolic state in which your body burns fat instead of carbs as its primary fuel source. Diabetic ketoacidosis is a serious complication in type 1 diabetes in which blood sugars run high and excess ketones are produced.

The keto diet has been shown to significantly lower blood sugar levels in people with type 1 and 2 diabetes (1, 3).

One 2.5-year study in 11 adults with type 1 diabetes found that the keto diet significantly improved A1C levels, a marker of long-term blood sugar control (1).

However, some participants experienced episodes of their blood sugar levels falling too low. This can happen if your blood sugar levels drop below 70 mg/dl (3.9 mmol/L) and is likely due to improper insulin dosing.

The keto diet raises the risk of your blood sugar levels becoming too low. This could lead to potentially serious complications, such as confusion, dizziness, slurred speech, and loss of consciousness (4, 5).

Summary The keto diet can considerably lower blood sugar levels in people with type 1 and 2 diabetes. Without proper insulin adjustments, your levels may become too low, leading to potentially serious complications.

Strong evidence suggests that the keto diet can promote weight loss (6).

A number of factors are believed to be responsible, including:

  • Appetite suppression. The keto diet promotes feelings of fullness, likely due to changes in hunger hormones, making you less likely to overeat (7).
  • Food elimination. Higher-carb foods are eliminated, reducing your calorie intake (8).
  • Higher protein intake. Keto diets tend to be higher in protein than standard diets, leading to increased fullness at meals (9).

While some people with type 1 diabetes may be interested in losing weight, this is not the goal, or even safe, for everyone.

It’s important to take this possible side effect into consideration before starting the keto diet.

Summary Following a keto diet may lead to weight loss, which may be undesirable or unsafe for some people, especially those who are underweight.

To control their blood sugar, people with type 1 diabetes use short-acting insulin in varying doses that depend on how high their blood sugar levels are and how many carbs a given meal contains.

When drastically reducing your carb intake, such as with the keto diet, blood sugar levels trend much lower, requiring less insulin to manage them.

For instance, a study in 10 people with type 1 diabetes on a low-carb diet found that participants needed an average of 20 fewer units of insulin per day (10).

Insulin dosing must be properly adjusted to account for your current blood sugar levels, which will likely be lower after starting the keto diet.

If you administer the same amount of insulin as before starting the diet, you may experience hypoglycemia (low blood sugar), a serious side effect.

Considering that less insulin is required, it’s crucial to seek medical guidance and test your blood sugar levels frequently to prevent episodes of hypoglycemia.

Summary On a keto diet, blood sugar levels run lower due to reduced carb intake. If you have type 1 diabetes, you may need to decrease insulin accordingly. This reduction should be supervised by your doctor.

Whether the keto diet is safe for people with type 1 diabetes does not have a simple yes-or-no answer. Many factors need to be considered.

If your diabetes is well managed and you thoroughly educate yourself and seek medical guidance, the keto diet can be a relatively safe option (11, 12).

However, it’s best to experiment with a lower-carb diet before implementing a full keto diet to see how your body responds.

Don’t start keto unsupervised

If you have type 1 diabetes and are interested in the keto diet, it’s extremely important to start by seeking medical guidance from a registered dietitian (RD) and medical doctor (MD).

An RD can assist you with the specific format and outline of the diet, whereas your doctor can help adjust your insulin regimen or oral medications accordingly.

Together, their supervision and guidance will greatly reduce your risk of serious complications and help you adhere to the diet safely and sustainably.

Make sure to monitor your ketone levels

In addition to closely monitoring your blood sugar levels, be sure to test your ketone levels regularly when following a keto diet.

Many people with type 1 diabetes may be familiar with ketone testing already, as it’s used to detect early stages of diabetic ketoacidosis (13).

There are several methods for testing ketones:

  • Blood testing. You can purchase meters with test strips that work similarly to blood glucose meters.
  • Urine testing. You can buy test strips that indicate ketones by color when submerged in a urine sample.
  • Breath analyzer. These devices measure acetone levels, a ketone byproduct, in your breath.

Specifically, you should check your ketone levels if your blood sugar level is above 300mg/dl (16.6 mmol/L) or you’re feeling sick, confused, or in a fog (13).

Blood ketone meters tend to be the most accurate and are readily available online or in pharmacies. Urine strips and breath analyzers can be purchased as well.

Some people should avoid the keto diet

Due to potentially negative overall health effects, some people with type 1 diabetes should not follow a keto diet, including:

  • those with a history of chronic low blood sugar levels
  • people who are underweight or have an eating disorder
  • people undergoing or recovering from a medical procedure
  • children or adolescents under 18 years old
  • pregnant or breastfeeding mothers

These populations have an increased risk of complications and are not advised to start a keto diet without medical clearance (5, 14).

Summary Some people with type 1 diabetes can safely follow a keto diet, though close medical supervision is crucial. Other groups of people should avoid the diet. It’s important to monitor ketone levels, especially if your blood sugar levels are elevated.

Whether the keto diet is safe if you have type 1 diabetes depends on many individual factors, such as how well your diabetes is managed or whether you’re underweight or have a history of low blood sugar levels.

With proper medical guidance, the keto diet can be a relatively safe option for some people with type 1 diabetes while others should avoid it altogether.

It’s best to start by trying a lower-carb diet before implementing a full ketogenic diet to gauge how your body responds.

If you have type 1 diabetes and want to try the keto diet, speak to your healthcare provider and a dietitian to set up a personalized program to minimize your risk of potentially dangerous side effects.