What Causes High Blood Sugar Levels?

Our blood sugar levels go up and down throughout the day. That’s normal. But did you know that your blood sugar can reach dangerous levels?

In this article, we will discuss what those levels are, how you can tell if you have high blood sugar, symptoms to look out for, and what complications could arise if it’s left untreated.

What is high blood sugar?

In general, healthy blood sugar levels are around 100 mg/dL. Once your blood sugar levels are above 270 mg/dL (which is 15 mmol/L), the risk of ketoacidosis becomes significant. This can be a dangerous situation, so look out for symptoms such as extreme thirst, dry mouth, abdominal pain, and confusion.

High blood glucose levels (above 600 mg/dL or 33 mmol/L) can lead to a dangerous situation called a hyperosmolar hyperglycemic nonketotic syndrome.

When looking at the long term, a hemoglobin A1c level higher than 6.5% increases your chances of developing complications of diabetes.

A high-fructose diet is a significant contributor to insulin resistance and metabolic syndrome. This can disturb the function of both tissues and organs as well.

For the most part, fructose is absorbed into the blood by two different transporters, called glucose transporter 2 and glucose transporter 5 (called GLUT2 and GLUT5 for short). The liver then metabolizes fructose to produce glucose, lactate, triglyceride, free fatty acid, uric acid, and methylglyoxal.

High levels of these metabolites are directly dangerous to the body.

During fructose metabolism, there is a depletion of a molecule called ATP. This depletion causes oxidative stress and inflammation response. This disturbs the functions of the local tissues and organs. This then leads to the overproduction of inflammatory cytokines, adiponectin, leptin, and endotoxin. These metabolites are dangerous indirect factors to the body.

Therefore, fructose and its metabolites, directly and indirectly, cause oxidative stress, chronic inflammation, blood vessel dysfunction, and leaky gut. All this can then further aggravate metabolic syndrome due to tissue and organ dysfunction.

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What does it mean for your blood sugar to be high?

Let’s first discuss what a normal, healthy blood sugar level is. A person without diabetes will generally have a blood sugar between 4.0 and 5.9 mmol/L before a meal. Their blood sugar usually is less than 7.8 mmol/L after a meal.

People with type 2 diabetes who have high blood sugar will have pre-meal levels higher than 4 to 7 mmol/L. After a meal, high blood sugar is considered anything higher than 8.5 mmol/L.

For those with type 1 diabetes, blood sugar is considered high when it is above the range of 5 to 7 mmol/L upon first waking up. Before a meal, blood sugar higher than 4 to 7 mmol/L is considered too high. After a meal, someone with type 1 diabetes should have blood sugar between 5 and 9 mmol/L. Otherwise, this is deemed to be high.

What happens in your body when your blood sugar is high?

Overall, high blood sugar causes reactive metabolites to lead to cell stress and biochemical abnormalities.

High blood sugar triggers the mitochondrial electron transport chain in the cell to overproduce high amounts of superoxides. These lead to inflammation within the body.

Neurovascular units in the body are made up of nerve, glial, and vascular cells. A neurovascular unit responds to the biochemical changes created by the reactive metabolites that are made from having high blood sugar. This is what leads to complications of diabetes, such as diabetic retinopathy and nerve damage (neuropathy).

What are the symptoms of high blood sugar?

You can have your blood sugar levels tested at your doctor’s office. They may look at random blood sugar, which is the level of glucose in your blood at a random point in time (whenever you get your blood tested).

Your doctor may want to see fasting blood sugar, which is the amount of glucose in your blood without having a meal. Your doctor may also test hemoglobin ac 1, which gives an idea of what your blood glucose levels have been like over the past month or so. This shows long-term blood sugar levels.

You can also test your own blood sugar levels at home using a glucometer. This is usually done before breakfast and dinner.

Ask your doctor what time of day is best for you to test your blood sugar at home on your glucometer. If you have type 1 or type 2 diabetes or use insulin medication, your doctor may want you to test your blood sugar levels more often.

What are some side effects of high blood sugar?

Some of the early side effects of elevated blood sugar (those you might notice at first) include:

Some of the later side effects of high blood glucose appear when hyperglycemia goes untreated. This can cause ketones to build up in the blood and urine. This can lead to ketoacidosis, and the symptoms include the following:

  • Fruity-smelling breath

  • Vomiting

  • Shortness of breath

  • Xerostomia (this is the medical term for dry mouth)

  • Weakness

  • Abdominal pain

  • Confusion

  • Coma

What are the dangers and complications of high blood sugar?

Staying within the recommended ranges of healthy blood sugar levels prevents potentially dangerous short and long term effects on the body.

For people with diabetes, high blood sugar can cause dangerous complications. This is why proper blood sugar regulation is so important.

High blood sugar significantly increases the risk of cardiovascular disease in those with diabetes. This is due to high blood sugar’s effects on the blood vessels. One study looked at 1791 military veterans with type 2 diabetes.

They found that after a total of five to six years of glucose control treatment, the patients had a 17% lower risk of major cardiovascular events, such as heart attack and stroke.

One study looked at patients who underwent blood glucose tests at least five times within a week after an acute ischemic stroke. Three months after the stroke, neuropsychological assessments were administered. High blood sugar was proven to have a detrimental effect on cognitive impairment after a stroke.

High blood sugar is known to contribute to the development and progression of metabolic diseases significantly.

High blood sugar is also considered a major risk factor for the development of Alzheimer’s disease.

What causes high blood sugar?

The following foods can cause high blood sugar:

  • Trans fats

  • Margarine

  • Peanut butter

  • Spreads

  • Creamers

  • Frozen dinners

  • Some crackers/muffins/baked goods

  • White grains

  • White rice

  • White bread

  • White pasta

  • White bagels

  • Fruit-flavored yogurt

  • Sweetened breakfast cereals

  • Sweeteners

  • White sugar

  • Agave

  • Honey

  • Maple syrup

  • Dried fruit

  • Certain snack foods

  • Saltine crackers

  • Pretzels

  • Graham crackers

  • Potatoes

The following drinks can cause high blood sugar (hyperglycemia), followed by a sugar crash (hypoglycemia):

  • Soda/pop

  • Sweetened iced tea/lemonade

  • Flavored coffee drinks

  • Frappuccinos

  • Lattes

  • Fruit juice

Who is at greater risk for high blood sugar?

  • Those who are overweight or obese are at greater risk for high blood sugar. This is because the more fatty tissue you have, the more insulin resistance you have as well.

  • People who are sedentary are also at higher risk. This is because exercise helps to control weight, use glucose for energy, and make your cells more sensitive to insulin.

  • If you have a family history of diabetes mellitus, this can increase your risk of symptoms of high blood sugar. This is especially true if it was a parent or a sibling who had diabetes.

  • Certain races are at higher risk for high blood sugar. These include: black, Hispanic, indigenous, and Asian.

  • Older age leads to an increased risk of high blood sugar. This is thought to be because, as we age, we tend to exercise less and lose muscle mass. We often gain fat mass as well.

  • People with high blood pressure are at risk of high blood sugar too. If your blood pressure is higher than 140/90 mmHg, then you are at a notably higher risk. This is because of blood sugar’s effects on the blood vessels and inflammation.

  • High cholesterol can also put you at a higher risk of high blood sugar. This is especially true if you have high triglycerides and low high-density lipoprotein (HDL, often referred to as “good” cholesterol). This also leads to an increased risk of heart attack and stroke.

What medical conditions can cause your blood sugar to spike?

One medical condition that certainly causes blood sugar spikes is stress. This does not necessarily mean emotional stress but physical stress. It can occur in severe, prolonged illness under serious, life-threatening conditions. It can also happen with an acute illness, under non-life-threatening conditions.

Research has shown that periodontal disease can cause blood sugar to spike as well.

Glucocorticoid medications have also been shown to lead to a spike in blood sugar levels.

How can you balance blood sugar levels?

What medications are commonly used to treat high blood sugar?


When someone has symptoms of diabetes, is checking blood glucose, and gets diagnosed with type 2 diabetes, metformin is the go-to medication. Metformin works by lowering the production of glucose in the liver. It also improves your body’s sensitivity to insulin so that your body uses insulin more effectively.


These include glyburide (DiaBeta, Glynase), Glipizide (Glucotrol), and Glimepiride (Amaryl). They help control blood sugar by helping your body to secrete more insulin.


Meglitinides include Repaglinide (Prandin) and Nateglinide (Starlix). These work like sulfonylureas because they stimulate the pancreas to secrete more insulin. However, they work faster. The duration of their effect on the body is shorter.


These medications make the body’s tissues more sensitive to insulin. They include Rosiglitazone (Avandia) and Pioglitazone (Actose).

DPP-4 inhibitors

This group of medication helps to reduce blood sugar effects very modestly. It includes Sitagliptin (Januvia), Saxagliptin (Onglyza), and Linagliptin (Tradjenta).

GLP-1 receptor agonists

These are injectable medications. They work by slowing digestion to lower blood sugar levels. They include Exenatide (Byetta and Bydureon), Liraglutide (Victoza), and Semaglutide (Ozempic).

SGLT2 inhibitors

SGLT2 inhibitors prevent the kidneys from absorbing sugar back into the blood. In fact, they encourage the kidneys to release sugar from the body in urine. Medications in this group are Canagliflozin (Invokana), Dapagliflozin (Farxiga), and Empagliflozin (Jardiance).


Insulin is injected into the body. Names for this medication are glargine (Lantus) and Determir (Levemir).

What supplements can be used to treat high blood sugar?

Some supplements can be used to help manage blood sugar and prevent situations such as diabetic ketoacidosis.

Glucose Control is an all-natural, clinical-grade supplement designed to work as part of a healthy diet and lifestyle to help manage type 2 diabetes. Glucose Control is formulated to lower your HBA1c levels and restore normal insulin sensitivity.

Containing powerful ingredients, clinically proven to lower blood sugar levels, Glucose Control effectively works to normalize insulin and blood sugar levels and restore optimal health.

The following supplements can also be used to treat high blood sugar levels:

  • Momordica charantia

What lifestyle changes can help lower your blood sugar?

To help lower your blood sugar, reduce your intake of foods that are high on the glycemic index.

It is also essential to take the medications that your doctor has prescribed to you.

Finally, exercise can help to prevent insulin resistance as well as manage weight, which contributes to blood sugar levels itself.

You should now be aware of the potential causes of high blood glucose and how to avoid them. If you suspect you may have high blood sugar, you must speak to your health care provider about this.

I’m sure you understand why this is important, now that you know of the potential dangers that high blood sugar can lead to. As always, leading a generally healthy lifestyle with a proper diet and exercise is best practice here.

Explore More


11 Signs And Symptoms Of High Blood Sugar To Be Aware Of.


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