For individuals managing type 1 diabetes, the ketogenic diet presents a complex landscape of potential benefits and risks. This article explores the existing research and expert opinions to provide a comprehensive overview of the keto diet's effects on blood sugar control, insulin needs, and overall health for those with type 1 diabetes.
Understanding the Ketogenic Diet
The keto diet is characterized by a significant reduction in carbohydrate intake, typically less than 50 grams per day, coupled with a high fat intake. This metabolic shift induces nutritional ketosis, where the body primarily utilizes ketones in the blood for energy instead of glucose. In ketosis, only ketone levels are elevated, allowing the body to use mostly fat for energy.
Ketosis vs. Diabetic Ketoacidosis (DKA)
It's crucial to differentiate between nutritional ketosis induced by the keto diet and diabetic ketoacidosis (DKA), a medical emergency. DKA primarily occurs in individuals with type 1 diabetes when they don't take insulin. Without insulin to transport blood sugar into the body’s cells, blood sugar and ketone levels rise rapidly, disrupting the blood’s acid-base balance. In diabetic ketoacidosis, blood sugar and ketone levels are very high, resulting in a critical health state.
Potential Benefits of Keto for Type 1 Diabetes
Research suggests several potential benefits of the keto diet for individuals with type 1 diabetes.
Improved Blood Sugar Management
The keto diet has been shown to significantly lower blood sugar levels in people with type 1 diabetes. A small 2018 study in 11 adults with type 1 diabetes found that the keto diet significantly improved A1C levels, a long-term blood sugar management marker. A 2024 study that followed one individual with type 1 diabetes for 10 years found that the keto diet improved blood sugar management and reduced daily insulin needs. Another 2023 study in a 20-year-old male with type 1 diabetes found that the keto diet reduced daily insulin needs and improved quality of life.
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Reduced Insulin Needs
When drastically reducing your carb intake, such as with the keto diet, blood sugar levels trend much lower, requiring less insulin to manage them. One possible reason for improved diabetes management is the need for insulin is less, given the restricted amount of carbohydrates, Snyder added.
A 10-year study of a patient with type 1 diabetes on a ketogenic diet showed a 43% decrease in daily insulin requirements. Ranjan et al15 conducted a small, randomized crossover study of a high-carbohydrate vs low-carbohydrate diet in patients with type 1 diabetes. The diets resulted in similar basal insulin requirements, but the total bolus dosage was lower in the low-carbohydrate diet group (defined as ≤ 50 g carbohydrates per day), with the total daily insulin dose reduced by 44.3%. This is similar to that observed in clinical trials in patients with type 2 diabetes starting a low-carbohydrate diet, in which insulin dosages are typically decreased by 50%.
Weight Loss
The keto diet promotes feelings of fullness, making you less likely to overeat. Higher-carb foods-which can be more calorie-dense-are eliminated, which can help reduce your calorie intake. Keto diets tend to be higher in protein than standard diets, increasing fullness at meals.
Potential Risks and Considerations
Despite the potential benefits, the keto diet also poses several risks for individuals with type 1 diabetes.
Hypoglycemia
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). If your blood sugar levels become too low, you may experience: confusion, dizziness, slurred speech, loss of consciousness. If you administer the same amount of insulin as before starting the diet, you may experience hypoglycemia (low blood sugar), a serious side effect.
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The keto diet may reduce your body’s insulin requirements, according to some research. That’s one of the benefits of the keto diet for diabetes, but the downside is it can lead to hypoglycemic episodes in some people, especially those with type 1 diabetes. Insulin dosages usually need to be reduced after starting a ketogenic diet; in type 1 diabetes, this usually entails decreasing the amount of insulin received per gram of carbohydrate.
Diabetic Ketoacidosis (DKA)
Researchers acknowledge that ketoacidosis on the keto diet for people with type 1 diabetes is a real concern. SGLT-2 inhibitors are associated with an increased risk of euglycemic DKA, particularly in type 1 diabetes. Accordingly, SGLT-2 inhibitors should be stopped before starting a ketogenic diet owing to the risk of DKA that often presents as euglycemic, making it difficult to recognize. GLP-1 receptor agonists, when used in type 1 diabetes, may increase the risk of hypoglycemia and DKA.
Nutrient Deficiencies
The very low-carb nature of the keto diet means sacrificing certain macro- and micronutrients necessary for general health. One drawback to the keto diet is inadequate fiber intake. Fiber is beneficial for glucose management as it doesn’t cause blood sugar spikes the same way other foods might. It’s also good for your heart. If trying the keto diet, Snyder added that you may need to supplement with thiamin and other vitamins including B6, C, D, and E.
Heart Health Concerns
The keto diet can cause spikes in cholesterol, sometimes dramatically, studies have found. Too much cholesterol, especially LDL (the bad kind; think “L” for “lousy”), can increase your risk of heart attacks and other forms of heart disease.
Safe Implementation of Keto for Type 1 Diabetes
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 you have type 1 diabetes and are thinking about trying a ketogenic diet, it is important to work with healthcare professionals, such as a registered dietitian and medical doctor, to avoid serious complications. 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 your doctor.
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Medical Supervision
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.
Blood Glucose and Ketone Monitoring
When following a keto diet, you should also closely monitor your blood sugar levels and test your ketone levels regularly. You should check your ketone levels if your blood sugar level is above 240mg/dl or if you: have difficulty breathing, have fruity-smelling breath, are vomiting. If your blood sugar levels are above 300 mg/dL, or if you experience any of the symptoms listed above, you should seek emergency services immediately.
Methods for Monitoring Ketones:
- Blood testing: You can purchase meters with test strips that work similarly to blood glucose meters. Blood ketone meters are the most accurate and readily available online or in pharmacies.
- 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.
Insulin Adjustment
Insulin dosing must be properly adjusted to account for your current blood sugar levels, which will likely be lower after starting the keto diet. Considering that less insulin is required, it’s crucial to seek medical guidance and frequently test your blood sugar levels to prevent hypoglycemia episodes.
Discontinuation of SGLT-2 Inhibitors
SGLT-2 inhibitors should be stopped before starting a ketogenic diet owing to the risk of DKA that often presents as euglycemic, making it difficult to recognize.
Starting the Keto Diet
Snyder recommends the following food sources for starting on the keto diet:
- Carbs: Aim for vegetables as much as possible, though whole grains, legumes, and fruit can work in small doses.
- Protein: Lean meats, fish, nuts, and seeds as opposed to saturated fat-laden meats like sausage and bacon.
- Healthy fats: Nuts, seeds, some oils (like olive oil), again avoiding sources of saturated fat.
Foods to avoid (or limit) on the keto diet include bread, pasta, alcohol, sugary drinks (including fruit juice), and starchy vegetables like potatoes. Snyder reminds people trying the keto diet that they may have to supplement with fiber and multivitamins.