Blood Sugar Control On A Keto Diet

The ketogenic diet is a high-fat, low-carb eating pattern that can help manage type 2 diabetes by improving blood glucose levels and reducing the need for insulin. Ketosis is a metabolic state achieved when the body is deprived of carbohydrates, causing it to use fat for energy instead of glucose. While the keto diet can be beneficial for people with diabetes, it also carries risks, including hypoglycemia and diabetic ketoacidosis, and should be carefully monitored by a doctor.

What is blood glucose?

Blood glucose, also known as blood sugar, is the amount of sugar circulating in your blood. When you eat food, your blood sugar will rise and fall—this is a normal process. However, the degree to which your blood sugar spikes depends on the food you eat. For example, a high-carb meal will cause a more significant spike in blood glucose than a low-carb, high-fat meal.

Glucose is a type of sugar that you get from the food you eat, and your body uses it for energy. As glucose travels through your bloodstream to your cells, it is called blood glucose or blood sugar. Insulin is a hormone that moves glucose from your blood into your cells for energy and storage. If you have been diagnosed with diabetes, you have higher-than-normal levels of glucose in your blood, either because you don't have enough insulin or because your cells don't respond well to insulin.

High blood glucose levels over a long period can damage your kidneys, eyes, and other organs, increasing your risk of diabetes and heart disease. Doctors use a blood glucose test to diagnose type 2 diabetes. Blood glucose levels can be monitored through blood glucose tests, which involve taking a small sample of blood to test the amount of sugar in it. People can purchase blood glucose monitors for use at home.

To maintain healthy blood glucose levels, it is important to eat moderate amounts of carbohydrates and focus more on complex carbohydrates while limiting simple carbohydrates. Exercise, regular meals, adequate sleep, and weight management are also crucial factors in maintaining healthy blood sugar levels.

How does ketosis affect blood sugar?

Ketosis is a metabolic state in which the body uses ketone bodies—created from fatty acids—as its primary source of energy, instead of glucose. This state is achieved when the body is deprived of carbohydrates.

Ketosis and blood glucose trends

When following a keto diet, the body switches from using exogenous glucose (from outside the body) for energy to glycogen (stored glucose). This causes specific metabolic changes.

The body can also produce its own glucose via gluconeogenesis, a process that ensures organs like the liver, which require glucose, get enough to function properly.

Ketone levels are measured via beta hydroxybutyrate (BHB) in the bloodstream. BHB levels within a 0.5 mmol/L - 1.0 mmol/L range is considered "light nutritional ketosis", while levels within 1.0 mmol/L- 3.0 mmol/L are considered "optimal" ketosis.

On a keto diet, blood glucose levels usually hover between 70-90 mg/dL. This is because carbohydrates have the most influence on glucose levels, and keto diets limit carbohydrate intake.

Elevated fasting glucose levels

Elevated fasting glucose levels are common in individuals who have been on a strict keto diet for over a year. This is a natural adaptation, with the body ensuring that glucose is present for organs that require it.

High glucose spikes from small amounts of carbs

Keto diets can lead to temporary physiological insulin resistance, where the body overreacts when carbs are introduced. This is different from pathological insulin resistance, which is a disease state.

In physiological insulin resistance, the muscles, which typically prefer glucose, start to prefer fatty acids for fuel. As muscles are a huge sinkhole for glucose, consuming carbs tend to cause larger glucose elevations.

Testing ketosis and blood glucose

Ketone and glucose levels are interconnected, and checking your glucose via a continuous glucose monitor (CGM) can provide real-time feedback on your diet and daily habits.

Identifying your carb threshold will help maintain metabolic flexibility, allowing your body to quickly shift from using ketones and glucose without being dependent on just glucose.

Tips for monitoring glucose on a keto diet

• Test your carb threshold: Gradually increase your carbohydrate intake while monitoring ketones and glucose values through a CGM. You can keep bumping up your carbs until your morning ketones drop below 0.5.
• Test your trigger foods: Record your pre-prandial (before eating) ketone and glucose value, then eat your experimental food choice. Two hours after your meal, record your postprandial (after eating) values to see how quickly your body recovered.
• Test your protein threshold: The threshold for "excess" protein is typically high, but anything in excess will lead to energy storage. Continuously monitoring your glucose will help catch subtle glucose rises that occur when too much protein is eaten.

Ketosis and blood sugar are closely linked. Ketosis can help manage blood sugar levels, but it's important to monitor both ketone and glucose levels to ensure your body is getting the fuel it needs while avoiding potential health risks.

How to test blood sugar

Testing your blood sugar can give you an insight into your body's response to specific foods, as well as helping you to manage your weight and health.

How to Test Your Blood Sugar

You can buy a blood glucose testing kit from a pharmacy without a prescription. Your healthcare provider can help you choose the right kit, set up the meter, and teach you how to use it.

The kit will include small needles (lancets) that fit into a spring-loaded plastic device, and a logbook for recording your numbers.

To test your blood sugar, prick your finger with the needle and place a drop of blood on a special strip. The meter will then display your blood glucose level.

You can also use your forearm, thigh, or the fleshy part of your hand to obtain a blood sample.

When to Test Your Blood Sugar

The best times to check your blood sugar are before meals and at bedtime. Your healthcare provider may also ask you to check your blood sugar two hours after a meal or in the middle of the night.

You should also test your blood sugar:

• If you are experiencing symptoms of low blood sugar (hypoglycemia)
• After eating out, especially if you have consumed foods you don't normally eat
• Before or after exercising
• If you have been under a lot of stress
• If you have eaten too much or skipped meals
• If you are taking new medications
• If your blood sugar has been higher or lower than normal
• If you are drinking alcohol

Tracking Your Blood Sugar

It is important to keep a record of your blood sugar levels, as this will help you and your healthcare provider to understand your body's response to your diabetes care plan. You can record your blood sugar levels in a logbook, or use an app or software provided by the manufacturer.

Interpreting Your Blood Sugar Results

Write down your blood sugar level and note any factors that may have affected it, such as food, activity, and stress. Look for patterns in your blood sugar levels and adjust your diabetes care plan accordingly.

Remember that blood glucose results can trigger strong feelings, but try not to use the numbers to judge yourself. Instead, focus on using them as a tool to help manage your health.

What is a normal blood sugar level?

Blood glucose is the amount of sugar circulating in your blood. Your blood sugar will rise and fall when you eat food. This is a normal process. However, how high your blood sugar spikes can depend on the food you eat. For example, a high-carb meal will spike your blood glucose much more than a low-carb, high-fat meal.

Higher than normal blood glucose levels can cause damage to the body, increasing the risk of diabetes and heart disease. Doctors even use a blood glucose test to diagnose type 2 diabetes.

According to the American Diabetes Association (ADA), a normal fasting blood sugar level in someone who does not have diabetes is between 70 and 100 mg/dL (3.9 to 5.6 mmol/L). Fasting blood sugar that consistently falls in the range of 100 to 125 mg/dL (5.6 to 6.9 mmol/L) is considered prediabetes, or impaired fasting glucose. If your fasting blood sugar is above 126 mg/dL (7.0 mmol/l) on two separate occasions, then you may have diabetes.

The ADA also states that a normal post-meal blood sugar reading one or two hours after a meal is below 140 mg/dL (7.8 mmol/L). However, some clinicians and individuals who are more cautious about high blood sugar may prefer using a carb-restricted approach targeting a post-meal blood sugar level of 120 mg/dL (6.7 mmol/L) or lower.

If your blood sugar is consistently 140 mg/dL (7.8 mmol/L) or higher but less than 200 mg/dL (11.1 mmol/L) when measured two hours after beginning a meal, you may have prediabetes or impaired glucose tolerance. If your blood sugar measurements are consistently 200 mg/dL (11.1 mmol/L) or higher two hours after beginning a meal, you likely have diabetes.

If your blood sugar levels are higher than normal, you may have prediabetes or diabetes. If you suspect you have either of these conditions, you should see your healthcare provider as soon as possible.

If your blood sugar levels are lower than normal, this is known as hypoglycemia. In people with diabetes, low fasting blood sugar levels can occur if your medication does not match your carbohydrate intake. It is important to let your healthcare provider know if you are following a low-carb diet so they can adjust your medication to match your carb intake.

In people who do not have diabetes, low fasting blood sugar levels are very rare. However, if low blood sugars do occur, they may be the result of a serious underlying medical condition such as an eating disorder or a tumor. If your fasting blood sugar is low and you do not take diabetes medications, see your healthcare provider.

How to measure blood sugar

You can measure your blood sugar levels with a blood sugar meter (also known as a glucose meter or glucometer). These are inexpensive and easy to find. Simply place a test strip in your blood sugar meter, prick the side of your finger with the lancet to draw a drop of blood, place the tip of the test strip on the drop of blood, and you will get a reading after a few seconds.

What to do if your blood sugar is high or low?

High Blood Sugar

High blood sugar, or hyperglycaemia, is common in people with diabetes. It can also affect pregnant women with gestational diabetes and, occasionally, people who don't have diabetes but are seriously ill, such as those who have recently had a stroke or heart attack, or have a severe infection.

If you have diabetes, your blood sugar can become high if you:

• Take too little insulin or the wrong type of insulin.
• Don't time your insulin and carb intake correctly.
• Take too little oral diabetes medication.
• Are less active than usual.
• Are physically or emotionally stressed.

If you don't have diabetes, high blood sugar can be caused by:

• Obesity, especially excess fat around your belly and organs.
• Physical inactivity.
• A diet of highly processed, high-carb foods and saturated fats.
• Certain medications, including corticosteroids, some blood pressure medications, HIV treatments, and psychiatric medications.
• Hormonal conditions, such as Cushing's syndrome and Acromegaly.
• Pregnancy.
• Inherited genetic conditions, such as Rabson-Mendenhall syndrome.
• Pancreatic conditions, such as chronic pancreatitis, cystic fibrosis, or pancreatic cancer.

High blood sugar can lead to severe complications, including:

• Nerve damage.
• Eye disease.
• Kidney damage.
• Diabetic ketoacidosis (DKA), which can lead to a diabetic coma.
• Hyperosmolar hyperglycaemic state (HHS), severe dehydration.

If you have high blood sugar, you should:

• Take your insulin or diabetes medication as prescribed.
• Follow your healthcare provider's instructions about food and exercise.
• Check your blood sugar regularly.
• Consult your healthcare provider to adjust your diabetes management plan if needed.

Low Blood Sugar

Low blood sugar, or hypoglycaemia, usually affects people with diabetes who take insulin or other diabetes medications. It is rare in people without diabetes.

Low blood sugar can be caused by:

• Taking too much insulin.
• Problems with the way you inject insulin, such as injecting in the same place too often.
• Missing or delaying meals, or not eating enough carbohydrates.
• Doing a lot of exercise without eating more carbohydrates or reducing your insulin dose.
• Drinking alcohol, especially without eating.

If you have low blood sugar, you should:

• Eat or drink something that will quickly raise your blood sugar, such as fruit juice, a sugary drink, glucose or dextrose tablets, jelly babies, or glucose gel.
• Check your blood sugar after 10 to 15 minutes.
• If your blood sugar is still low, have another sugary snack or drink, and check again after 10 minutes.
• Once your symptoms have improved and your blood sugar is above the recommended level, eat something to keep your blood sugar up, such as biscuits, a sandwich, or your next meal.

If someone has very low blood sugar and becomes unconscious:

• Do not give them food or drink as they won't be able to swallow safely.
• Put them in the recovery position.
• Give them a glucagon injection if one is available and you know how to use it.
• If they start to recover within 10 minutes and can swallow safely, give them something to eat or drink to raise their blood sugar.
• Stay with them until they're fully recovered.

To reduce the risk of low blood sugar:

• Follow your diabetes treatment plan, including adjusting your insulin dose as needed.
• Check your blood sugar regularly.
• Carry something to quickly raise your blood sugar, such as sugary drinks, sweets, or glucose tablets.
• Carry a glucagon injection kit and medical ID.
• Ensure your family and friends know how to treat severe low blood sugar.
• Ask your care team about a continuous glucose monitor or flash monitor.
• Do not skip or delay meals.
• Avoid excessive alcohol consumption, especially without eating.
• If you drive, check your blood sugar before and during each journey, and do not drive for at least 45 minutes after your blood sugar returns to normal.

Frequently asked questions