Keto Diet and Diabetes: Is It Safe?

A keto diet is a popular low-carb diet trend, but is it safe if you have diabetes? Many swear by it as an effective way to lose weight and manage blood sugar. While some research shows benefits for the keto diet and diabetes, this eating pattern isn’t right for everyone.

Here’s how a keto diet works, plus the pros, cons, and potential dangers of ketosis for diabetics.

What Is a Keto Diet?

A keto (short for ketogenic) diet is very low in carbohydrates and very high in fat. Usually, your body uses glucose from carbohydrates for fuel. A keto diet forces your body to use fat as fuel instead.

When you follow a keto diet:

  • About 70% of calories come from fat-rich foods like nuts, avocados, and cream.
  • Another 20% of calories come from protein foods like salmon, eggs, and cheese.
  • Less than 10% of your daily calories come from carbohydrates like fruit, vegetables, beans, and grains.

On this diet, most people must restrict carbohydrates to between 20 grams and 50 grams daily. To put that in perspective, one small apple or one-third cup of cooked rice each has about 15 grams of carbohydrates.

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Keto Diet and Diabetes

With type 2 diabetes, your insulin doesn’t work as well as it should. Insulin’s job is to remove glucose (sugar) from your blood and pump it into your cells. As a result, your blood sugar is higher than average, especially after a carbohydrate-rich meal.

High blood sugar for long periods increases your risk of having a heart attack or stroke. It also makes it harder to lose weight. And being overweight, especially if you have excess belly fat, makes it even harder for your insulin to work.

The keto diet may benefit people with type 2 diabetes because it severely restricts carbohydrates. It prevents spikes in your blood sugar after eating and makes it easier to maintain healthy blood sugar levels. And many people find that a keto diet promotes weight loss, which also helps your glucose levels.

Research on the keto diet and diabetes shows it may help:

  • Reduce your A1C levels (a three-month average blood sugar).
  • Reduce fasting blood sugar.
  • Promote moderate weight loss.
  • Reduce the amount of diabetes medication you need.
  • Improve your triglyceride levels.

Ketosis and diabetes

The potential benefits of the keto diet come from something called ketosis. That’s when your body runs out of glucose and switches to fat as your primary fuel source. When you’re in ketosis and burning fat, your body produces ketones.

Ketosis is a metabolic state that happens after about four days of eating a very low carbohydrate diet. Ketosis can also occur when you fast or are sick and don’t eat for a few days.

Although they sound similar, ketosis differs from ketoacidosis (also called diabetic ketoacidosis). Ketoacidosis is a serious complication of type 1 (insulin-dependent) diabetes. (Although uncommon, it can also happen with type 2 diabetes.)

Ketoacidosis happens when you don’t have enough insulin to clear glucose out of your blood. When insulin levels are too low, blood sugar and ketones can become dangerously high, causing ketoacidosis.

Ketones are acids your body makes when you break down fat for energy. Normally, they’re excreted in your urine, but with type 1 diabetes, they can build up in your blood. If that happens, your blood becomes too acidic.

Ketoacidosis is a life-threatening condition for which you need immediate medical treatment.

Is a Keto Diet Healthy?

Some aspects of a keto diet are healthy. For example, if you have a sweet tooth, a keto diet helps you rein it in because desserts and sweets are off-limits. Eliminating sugary foods and beverages is great for diabetes because it quickly improves blood sugar.

But the major downside of a keto diet is that it also excludes many healthy foods. More than likely, you’ll have to avoid these healthy carbohydrate foods:

  • Most fruits.
  • Certain vegetables like carrots, parsnips, winter squash, and white and sweet potatoes.
  • Legumes (beans) like black, kidney, pinto beans, lentils, and chickpeas.
  • Whole grains like oatmeal, shredded wheat, and brown rice.
  • Certain dairy foods like milk and Greek yogurt.

Not only do these foods provide healthy carbohydrates for energy, but they’re also high in vitamins, minerals, and protein. Eliminating them might leave some gaps in your diet.

When planning meals for a keto diet, choose a good variety of low-carbohydrate foods to fill those gaps. A healthy keto diet includes:

  • Lots of low-carbohydrate vegetables like leafy greens, broccoli, Brussels sprouts, tomatoes, and mushrooms.
  • Small portions of berries, like blueberries, strawberries, and raspberries.
  • Dairy foods, like cheddar, mozzarella, or cottage cheese.
  • Lean proteins, like chicken, fish, and eggs.
  • Healthy fats, like avocados, nuts and seeds, nut butter, and olive oil.

When planned properly, a keto diet provides the nutrients your body needs. Still, your health care provider may also recommend taking a multivitamin and mineral supplement as added insurance.

Potential Dangers of Ketosis for Diabetics

There are several potential problems that diabetics on a keto diet may face.


One of the biggest dangers of ketosis for people with diabetes is the risk of hypoglycemia or low blood sugar. It can happen if you follow a keto diet and use insulin or other blood sugar-lowering medications. Symptoms of hypoglycemia include:

  • A fast heartbeat.
  • Shaking.
  • Dizziness or disorientation.
  • Sweating.
  • Nervousness or anxiety.

Hypoglycemia is especially dangerous when driving or exercising because you can become disoriented or faint.

If you take insulin and want to try a keto diet, talk with your doctor. They can help you decide if a keto diet is right for you. They can also help you learn how to adjust your insulin to minimize the risk of hypoglycemia.

Increase in LDL (bad) cholesterol

Another concern with the keto diet is that it can potentially increase LDL (bad) cholesterol levels in some people. High LDL cholesterol increases your risk of heart disease. Eating lots of these saturated fat foods might increase your LDL cholesterol.

Examples of foods high in saturated fat include:

  • Bacon.
  • Sausages.
  • Fatty cuts of red meat, like ribeye steak.
  • Cheese.
  • Butter.
  • Cream.

If you want to try a keto diet, focus on heart-healthy fats to meet your fat requirement. Foods like olive oil, avocado, and nuts are less likely to raise LDL cholesterol.

Unpleasant side effects

Although not dangerous, it’s also worth noting that the keto diet may have some unpleasant or uncomfortable side effects. These are most common during the first few weeks of the diet and often include:

  • Constipation. This is common because the diet is low in fiber. To prevent it, eat plenty of high-fiber, low-carb vegetables like cauliflower, cabbage, and leafy greens.
  • Headaches and weakness. These can happen from low blood sugar as your glucose stores diminish.
  • A fruity or ammonia smell on your breath. This happens when you exhale ketones.
  • Muscle cramps and dehydration. With ketone production, you lose excess water and might develop electrolyte imbalances. Make sure you drink plenty of water and ask your health care provider if you need a sugar-free electrolyte supplement.
  • Diarrhea. A high-fat diet is harder to digest and might trigger diarrhea.

Many people find it challenging to plan meals and snacks that provide enough fiber and are nutritionally balanced. And because so many food groups are off limits, you might not get enough variety in your diet. It’s wise to work with a dietitian to ensure you’re meeting your nutrition needs while staying in ketosis.

It’s essential to work closely with your health care team while on the keto diet. Your doctor can ensure you get the right results while avoiding side effects.

Diabetes Spectrum. Low-Carbohydrate and Very-Low-Carbohydrate Diets in Patients With Diabetes. LINK

About Endocrinology

The UPMC Department of Endocrinology stands as a national leader in research of diabetes and endocrine conditions. We partner with the University of Pittsburgh Division of Endocrinology and Metabolism for research and clinical trials. We treat diabetes, obesity, osteoporosis, hormonal disorders, and thyroid disorders at several locations across our communities. We also have specialized Diabetes Centers to help you manage your disease. Find an expert near you.