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Why Does Blood Sugar Go Up When Fasting


How Does Lack Of Sleep Raise Your Risk

How To STOP Glucose From Rising After Waking Up! Listen Up!

Itâs hard to know for certain. Many studies have suggested that short sleepers have irregular eating habits, snack more, and are more likely to eat unhealthy foods.

Other research has found that shortchanging sleep can directly affect how the body makes other hormones, which in turn affect blood sugar. For example, when you stay up late, your body makes more of the hormone cortisol, which affects how insulin works.

Also, growing evidence shows that disrupting your bodyâs biological clock by being awake at night can make your cells more resistant to insulin. In one study, researchers altered the circadian rhythms of 16 healthy volunteers by allowing only 5 hours of sleep each night for 5 nights, much like a sleep-deprived workweek. When those volunteers ate food at night — a time when the body isnât biologically prepared for a spike in blood sugar — their bodies didnât use insulin normally.

High Fasting Blood Sugar On Keto

The more I coach people through a ketogenic lifestyle, the more I become familiar with small nuances that can affect different peoples experience. For example, there are a number of people who experience high fasting blood sugar upon waking in the morning. These individuals would express that they were following a ketogenic diet and were in a fasted state so it doesnt make sense to have elevated blood sugar.


What you are going to find out in this article is that this effect may actually be much more normal than you think. In fact, it may not even be an issue. That being said, for some people it may actually be a sign of something undesirable going on with their metabolism. This article will help you troubleshoot what is likely to be causing your high fasting blood sugar.

So Whats Making You High

As diabetics we are constantly striving to maintain a perfect blood glucose level. Having a high fasting reading constantly is a cause for major concern and can definitely affect your hbA1c and by extension your health if not corrected. For 3 or 4 days in a row, plan specific blood glucose testing times. You should also prepare your own meals during this testing period so that you are certain of the carbohydrate content. Try to have your last meal at least 2 hours before bedtime. Check your blood glucose at bedtime, wake up around 3 a.m to test again, and take the final reading at your usual wake-up time. Comparing these results can identify what is the underlying cause of your high blood glucose level in the morning. Sometimes it can also be a combination of issues. The table below is a guideline to follow to assist in identifying the problem. Always seek medical advice from your doctor pertaining to medication dosages and modifications.

Find the Culprit of your Fasting High Blood Glucose Level
Bedtime
Day 3
Day 4

If your 2 hour post dinner time is close to your bedtime there is no need to test again. If it is more than an hour apart include both tests. These are quite a lot of test which will be done over a couple day. Your fingers will be sore but it will lead to discovering your underlying problem.

Recommended Reading: What Happens In Type 1 Diabetes

Insulin And Blood Sugar

Insulin is an important hormone that helps regulate your blood sugar levels. The pancreas makes insulin. It helps control your blood sugar levels by assisting the cells that absorb sugar from the bloodstream.


If you have type 1 diabetes, your body doesnt make insulin. This means you have to inject insulin every day.

If diet and exercise arent enough to manage blood sugar, those with type 2 diabetes may be prescribed medications to help keep blood sugar levels within target ranges.

If you have type 2 diabetes, your body produces insulin, but may not use it properly or produce enough of it. Your cells dont respond to insulin, so more sugar keeps circulating in the blood.

Exercise can help the cells respond better and be more sensitive to insulin. The proper diet can also help you avoid spikes in blood sugar. This can help keep your pancreas functioning well since high blood sugar levels decrease pancreatic function.

Insulin Is Low An Important Difference

Trouble Controlling Your Blood Sugar? It Could Be âBrittle ...

Only testing fasting blood glucose without testing fasting insulin tells you very little. Thats because two people could have exactly that same fasting blood glucose levels and have very different circulating insulin levels.5


It is all about the relationship between glucose and insulin and how they work in concert. This is called the homeostatic model assessment of insulin resistance or HOMA-IR. The name is a mouthful, but it simply means that the body is always trying to keep its essential systems in balance or in an equilibrium called homeostasis. Insulin is working against glucose in an attempt to keep blood sugar levels stable, a.k.a in homeostasis.6

In one individual for example someone with pre-diabetes, type 2 diabetes, or polycystic ovarian syndrome insulin may over time be pulsed out in higher and higher amounts just to keep the blood sugar relatively stable. While fasting blood glucose could still be in the normal range, it is taking increasing amounts of insulin to keep it there. As insulin resistance develops, and insulin becomes increasingly ineffective to bring blood sugars down, blood sugars will eventually rise too high.

In a second individual someone who has been on the keto diet for a number of months and is now burning fat for energy much lower amounts of insulin are being pulsed by the pancreas to keep the glucose stable. You have now, therefore, improved your insulin resistance and only need small amounts of insulin to keep glucose in check.

Also Check: Life Of A Diabetic

Hashimotos Fasting And Keto

I believe there is a way to reverse Hash! I feel so much better on keto and IF than any treatment over the past three years. Have you had any patients reversing Hashi with this program?


Thank you so much for all your work for all of us,Martha

Answer: I dont see Hashimotos very frequently so dont have much experience. Fasting and low carb diets usually drop insulin so are effective for diseases of excessive insulin such as obesity, type 2 diabetes and PCOS. However, it may also have a smaller effect on inflammation so it may certainly benefit Hashimotos as well, but there are no studies to prove this, and I have only limited clinical experience with Hashimotos.

Dr. Jason Fung

When To Call A Doctor

When you have prediabetes, it’s important to watch for symptoms of type 2 diabetes. Call your doctor if you notice that you are:

  • Feeling very thirsty a lot of the time.
  • Urinating more often than usual.
  • Feeling very hungry a lot of the time.
  • Having blurred vision.

You may want to talk to your doctor about testing for prediabetes if you are:


  • Overweight and get little or no exercise.
  • Interested in reducing your risk for getting type 2 diabetes.

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Who Should Do The Test

According to the American Diabetes Association, screening for diabetes is recommended in people over 45 , or at any age if you have certain risk factors, including :

  • Being overweight, obese, or physically inactive
  • Having a close relative with diabetes
  • Belonging to a certain race/ethnic group
  • Having signs of insulin resistance or conditions associated with insulin resistance, such as high blood pressure , low good cholesterol and/or high triglycerides , and polycystic ovary syndrome
  • Having had diabetes in pregnancy

Roller Coaster: Female Hormones

WHY is my blood sugar UP AND DOWN? Role of diabetic medicines & diet in type 2 diabetes treatment.

When a woman’s hormones change, so does their blood sugar. Keep a monthly record of your levels to get a better idea of how your menstrual cycle affects you. Hormone changes during menopause may make blood sugar even harder to control. Talk to your doctor about whether hormone replacement therapy is a good idea.

Read Also: What Are The First Signs Of Diabetes

Symptoms Treatments And Prevention

Hyperglycemia means high glucose in the blood . Your body needs glucose to properly function. Your cells rely on glucose for energy. Hyperglycemia is a defining characteristic of diabeteswhen the blood glucose level is too high because the body isn’t properly using or doesn’t make the hormone insulin.


Eating too many processed foods may cause your blood sugar to rise.

A1c Is Better Associated With Chronic Complications Than Fpg

Different from National Diabetes Data Group criteria, which were essentially based on distribution of glucose levels within the general population, the 1997 ADA criteria established diabetic glycemic levels by means of their association with retinopathy, the most exclusive and specific diabetes complication. Various observational studies documented that an increased prevalence of nonproliferative diabetic retinopathy can be observed with fasting glucose levels around 7.0 mmol/L and 2-h PG around 11.1 mmol/L . Interestingly, the same studies documented that retinopathy increased with A1C levels around 6.5% . These results were confirmed in a more recent study including almost 30,000 subjects recruited in several countries. Such study clearly showed that prevalent retinopathy started to increase in the A1C category of 6.57.0% . Therefore, a cut point of A1C for diagnosing diabetes with an approach similar to the one used with FPG and 2-h PG is available .

It is well known that cardiovascular disease is the most frequent chronic complication of diabetes, with incidence rates 5- to 10-fold higher than with microvascular disease. For this reason, the association of A1C with CVD can be considered a major issue when discussing the potential use of A1C for diagnosing diabetes. In this regard, it is worth mentioning that, in the general population, FPG is a poor marker of future CVD events, whereas 2-h OGTT and A1C are good predictors .

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How Intermittent Fasting Affects Glucose Levels

When it comes to IF and blood glucose, the results are so much more than just calories and weight loss. IF is a boon for numerous bodily systems. It lowers blood glucose. It increases our bodiesâ sensitivity to insulin. It reduces inflammation. It makes our digestive and metabolic processes more adaptable, and it can even change when and how our bodies make blood sugar.


Its Strange That Blood Sugar In A Diabetic Can Rise Despite Not Having Eaten Anything Since Typically Eating Causes Blood Sugar To Go Up

Why Does Your Blood Sugar Go Up When You Don T Eat ...

But its no uncommon occurrence that in diabetes, glucose or blood sugar levels can actually rise in the absence of eating.

When we dont take food into our body for energy, our liver will try to help us by releasing glucose into our blood so we have the energy we need to stay alive, says Lucille Hughes, RN, CDE, director of diabetes education at South Nassau Communities Hospital in Oceanside, NY.

For people with diabetes, the liver may release too much glucose, causing blood sugar to go up.

This is why its so important for diabetics to regularly take blood sugar readings, even if they feel fine.

The liver has hundreds of jobs. One of those jobs is to release glucose into the bloodstream for energy because the body requires energy to function, even when at rest.


Basic bodily functions require energy and glucose provides that energy.

In diabetes, things are out of whack in the body. The liver in the diabetic may sometimes overestimate how much sugar to release into the bloodstream.

Or, to put it another way, the liver over-corrects the problem.

The only way that a diabetic can stay ahead of this curve is to monitor their glucose levels on a regular basis throughout the day to make sure that the sugar level doesnt sneak its way into getting into a dangerously high range.

Recommended Reading: What Happens If You Stop Taking Diabetes Medication


What Is The Dawn Phenomenon

Your body uses glucose for energy and it is important to have enough extra energy to be able to wake up in the morning. So for a period of time in the early morning hours, usually between 3 a.m. and 8 a.m., your body starts churning out stored glucose to prepare for the upcoming day.

At the same time, your body releases hormones that reduce your sensitivity to insulin. In addition, these events may be happening while your diabetes medication doses taken the day before are wearing off.

These events cause your body’s blood sugar levels to rise in the morning .

Controlling For Monitor Accuracy

Oftentimes I have seen that certain blood sugar monitors can have off readings every now and then. If you have an elevated reading that seems unexpected, take the same measure 2 more times and average the values, oftentimes an elevated reading can be a monitor malfunction.

Other things to consider are any kind of residues that are present on the surface that you tested. For example, if you recently held a piece of fruit or used a product that contained sugar then this can also throw off your monitor.


Make sure you wash the testing area thoroughly before testing and take multiple readings to ensure accuracy.

Monitoring both ketones and fasting blood sugar can be extremely helpful as well. This is because if your ketones are elevated at the same time as a slightly elevated blood sugar reading, this is a good gauge that you are still in ketosis. As I describe above, this scenario may be more likely to be adaptive glucose refusal. My favorite 2-in-one monitor is the Keto Mojo.

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How To Control Blood Sugar With Intermittent Fasting

If youd like to try intermittent fasting for blood sugar control, there are a few things for you to consider, especially if you have diabetes.

Choose an intermittent fasting plan that wont cause you stress. During your fast, your insulin levels decrease. In response, your body releases hormones from your liver, one of which is the stress hormone, cortisol. Cortisol tells the liver to release more glucose. So if youre in a state of stress, or if you have diabetes, your liver is more likely to over-react and release more glucose than you need. As a result, your blood sugar levels will increase.


If youre your blood sugar goes up, and you havent eaten, its likely your liver release glucose into your bloodstream. Exercise is a vital way to utilize sugar in your blood and help your body return to a fat-burning state.

Its uncommon, but fasting can cause you to experience hypoglycemia or low blood sugar. If you have diabetes, this can potentially be dangerous since diabetes medications already put you at risk for low blood sugar. Talk to your doctor about your intent to start a fast, especially if youre on diabetes medications. Its possible for you to fast safely when your doctor manages your diabetes medications appropriately.

When To See A Doctor

Dawn Phenomenon: High Fasting Blood Sugar Levels On Keto & IF

If a persons blood sugar levels are high more than three times in a 2-week period without an apparent reason, the National Institute for Diabetes and Digestive and Kidney Diseases recommend that they seek medical help.

Any significant change in blood sugar patterns warrants a visit to a doctor. People with diabetes and those at risk of diabetes should also consult a doctor if:

  • blood sugar levels become unusually high or low
  • well-managed blood sugar levels are suddenly start fluctuating
  • people have new or worsening symptoms of diabetes
  • they change their medication or stop using it

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Fasting And The Risks

As well as the abstinence from food , fasting is also usually a time of prayer, reflection and purification. If you treat your diabetes with certain medications such as insulin, there is also the danger of the blood sugar levels after fasting becoming too low. This can lead to a hypo, or having your blood sugar levels too high which can lead to diabetic ketoacidosis , which would require hospital treatment. The symptoms of DKA include feeling very thirsty and passing a lot of urine.

If someone is fasting and does not take in fluids to reduce their thirst, this will accelerate dehydration and they will require urgent admission to hospital.

You should always check with your GP or diabetes team if you are thinking about fasting, particularly if you’re not sure of what to do with your diabetes medications. If you can’t get hold of them, it would be advisable not to fast. And if you require urgent medical help you can use the NHS 111 online service.

Low Blood Sugar Levels

Blood sugar that is too low can cause symptoms such as:

  • shaking and sweating
  • headache
  • tiredness

As with low blood sugar, high blood sugar may cause loss of consciousness or seizures if people leave them untreated. Persistent high levels can increase the risk of serious complications that doctors relate to diabetes, such as cardiovascular disease.

Also Check: Can Diabetes Eat Cheese

Is Sugar Bad For You

If you love sweets, don’t despair. You don’t have to give them up forever. Sugar will raise your blood sugar levels more quickly than other carbs, but diabetes experts now say the total amount of carbs is most important. So keep your serving sizes small and take into account the total carbs and calories.

A Word About Lada Latent Autoimmune Diabetes In Adults

Non Fasting Blood Sugar Levels Chart

If all of the information in this post does not help you understand your rising blood glucose on the low-carb diet, and your blood glucose continues to rise higher and higher, not only in the morning but at other times of day, there may be a potential issue of latent autoimmune diabetes in adults , also sometimes called type 1.5 diabetes.11

Both Dr. Hallberg and Dr. Fung say they see LADA regularly among their patients who may have been misdiagnosed with type 2 diabetes and have LADA instead.

LADA is like type 1 diabetes in that antibodies are attacking the insulin-producing cells of the pancreas, but it arises in adulthood, not in childhood or adolescence. Diabetes researchers note that LADA also has features of type 2 diabetes, but the patients usually are thinner and progress to needing insulin faster because their insulin-producing beta cells have been attacked by antibodies. The highest rates of LADA are found in Northern Europe, with up to 14% of those with type 2 diabetes actually having it.12

I test serum C-peptide and insulin in everybody in my Intensive Dietary Management program, notes Dr. Fung. I re-check them over time and it often takes 6 months to 1 year to clinch the diagnosis. I would suspect about 5-10% of my type 2s are actually LADA.

Dr. Naiman has similar experiences and routines.13

Also Check: Non Diabetic A1c Range

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