Glucose comes from the Greek word for "sweet." It’s the simplest type of carbohydrate (carb), making it a monosaccharide, meaning “one sugar.”
Other monosaccharides include fructose, galactose, and ribose. In this form, dietary glucose and other carbohydrates eventually convert to blood glucose in the body.
Along with fat and prot, glucose is one of the body’s primary fuel sources. Especially important as an energy source for your brain and nervous system, where glucose constitutes more than 80% of the total brain energy requirement.
The primary source of glucose in the body is from dietary carbohydrates. When you consume foods rich in carbohydrates like bread, pasta, potatoes, and fruits, your digestive system breaks them down into smaller molecules, including glucose. The process can be explained in four parts:
Ingestion: When you eat foods containing carbohydrates, the process begins in the mouth where enzymes in saliva start breaking down complex carbohydrates into simpler sugars.
Digestion: The food then moves down the esophagus and enters the stomach. In the stomach, gastric acid and enzymes continue to break down the carbohydrates further.
Absorption: The partially digested food then moves into the small intestine, where specialized enzymes break down carbohydrates into individual sugar molecules, including glucose. The glucose is then absorbed into the bloodstream through the intestinal lining.
Circulation: Once absorbed, glucose enters the bloodstream and is transported to cells throughout the body, providing them with a source of energy.
Your body ideally uses glucose multiple times a day, and it is designed to keep the level of glucose in your blood constant.
When you eat, it quickly starts working to process glucose and other carbohydrates. Then, enzymes begin to break them down with help from the pancreas. Beta cells in your pancreas monitor your blood sugar level every few seconds. When your blood glucose rises after you eat, the beta cells release insulin into your bloodstream. Insulin acts like a key, unlocking muscle, fat, and liver cells so glucose can get inside them.
Most of the cells in your body use glucose along with amino acids (the building blocks of protein) and fats for energy. But it's the main source of fuel for your brain. Nerve cells and chemical messengers there need it to help them process information. Without it, your brain wouldn't be able to work well.
After your body has used the energy it needs, the leftover glucose is stored in little bundles called glycogen in the liver and muscles. Your body can store enough to fuel you for about a day.
After you haven't eaten for a few hours, your blood glucose level drops. Your pancreas stops churning out insulin. Alpha cells in the pancreas begin to produce a different hormone called glucagon. It signals the liver to break down stored glycogen and turn it back into glucose.
That travels to your bloodstream to replenish your supply until you're able to eat again. Your liver can also make its own glucose using a combination of waste products, amino acids, and fats.
Your blood sugar level normally rises after you eat. Then it dips a few hours later as insulin moves glucose into your cells. Between meals, your blood sugar should be less than 100 milligrams per deciliter (mg/dl). This is called your fasting blood sugar level.
There are two types of diabetes:
In type 1 diabetes, your body doesn't have enough insulin. The immune system mistakenly attacks and destroys the beta cells in the pancreas, which are responsible for producing insulin. Insulin is a hormone that regulates the levels of glucose in the bloodstream and facilitates its entry into cells for energy.
In type 2 diabetes, the body's cells become resistant to the effects of insulin, a condition known as insulin resistance. As a result, the pancreas tries to compensate by producing more insulin to overcome this resistance and maintain normal blood sugar levels. Initially, this increased insulin production helps to move glucose into the cells. However, over time, the continuous demand for high levels of insulin can strain the pancreas, leading to a decrease in its insulin-producing capacity. As a consequence, the pancreas becomes unable to produce enough insulin to meet the body's needs, and insulin deficiency may develop in later stages of type 2 diabetes.
Without enough insulin, glucose can't move into the cells. The blood glucose level stays high. A level over 200 mg/dl 2 hours after a meal or over 125 mg/dl fasting is high blood glucose, called hyperglycemia.
Too much glucose in your bloodstream for a long period of time can damage the vessels that carry oxygen-rich blood to your organs.
Normal levels of glucose mean that your regulating systems for balancing storage and availability of energy are intact. Maintaining normal levels of glucose will increase your chances of a longer and healthier life.
It is known that normal levels of glucose in blood is associated with a lower risk for developing cardiovascular disease. Tracking your glucose levels are important for early detection of prediabetes. It is estimated that approximately 17,8% of adults 18-74 in Sweden suffer from prediabetes, meaning that early detection and early lifestyle changes such as increased physical activity and a more healthy diet, could prevent the development of diabetes in almost 1,5 million Swedish adults!
Measuring your glucose can be relevant for several reasons:
Identifying early signs of risk for developing diabetes, so called prediabetes
Diagnosing diabetes
Tracking the effect of diabetes medication
Tracking the effect of lifestyle changes
Measuring biological age with the Levine cloc
High levels of blood glucose in your bloodstream, also known as hyperglycemia, mean that the body lacks sufficient effects of insulin. This glucose imbalance, if chronic, is what we call diabetes (mellitus). Depending on the underlying mechanism for causing the elevated glucose levels, it may be defined as various types of diabetes.
Elevated glucose levels can basically originate from two various causes individually or in combination:
More glucose in the bloodstream than what the produced and released insulin can handle
Impairment in the production, release or effectiveness of insulin
Excessive amounts of glucose can have many underlying causes, such as:
High intake of food
Physical inactivity
Stress
To learn more about what may increase your glucose levels, click here.
Impairment in production or effectiveness of insulin, also known as insulin resistance, many times derives from lifestyle, where obesity, physical inactivity, sleep deprivation and chronic stress are common causes. On top of this, increasing age is a risk factor as well as genetics.
There are several things that can make your blood glucose rise, such as:
Too much food
Especially foods high in carbohydrates
Physical inactivity
Results in a decreased metabolism of the sugars ingested through your diet keeping them longer in the circulating blood
Stress
Releases cortisol which results in an increase in blood sugar levels
Lack of insulin/diabetes medication
Side effects from other medications such as steroids and anti-psychotics
Pain
Short-term as well as long-term pain causes stress -> triggers the release of cortisol -> increases blood sugar levels
Dehydration
Due to a more concentrated blood
Skipping breakfast
Going without breakfast can cause an increase in blood glucose after having lunch and dinner
Illness
During illnesses, the immune system activation causes the release of hormones like adrenalin and cortisol to help in the process of fighting the pathogens. Both of which causes an increase in blood glucose levels
Medical conditions
Cushing’s syndrome
Hyperthyreosis
Liver cirrhosis
Feochromocytom
Pancreatic cancer
There are several symptoms of high blood sugar levels, such as:
Increased thirst and a dry mouth
Unintentional weight loss
Increased need to pee more frequently
Tiredness
Blurred vision
Recurrent infections, such as bladder infections and skin infections
Low blood sugar levels, also known as hypoglycemia, means that you have less circulating blood glucose in your bloodstream than what is healthy for you.
This may sound good at first, but the body needs energy, and glucose is the main source of cellular energy. If the levels are too low, there may not be enough energy for cells to function properly. Very low levels of glucose, most often seen in diabetes patients when overmedicating with insulin, may cause headaches, blurred vision, vomiting, irritability and confusion. In very rare and extreme cases, if no immediate medical attention is received, hypoglycemia can be fatal.
There are several things that can make you blood glucose fall, such as:
Lack of food
Not eating enough or eating foods lacking carbohydrates can decrease the levels of blood glucose
Physical activity
Results both in the use of energy through the metabolism of glucose, and makes your body more sensitive to the circulating insulin which also lower the blood glucose.
Too much insulin/diabetes medication
Side effects from medications
Such as certain antidepressants, beta-2-stimulators and corticosteroids
Medical conditions
Pituitary gland and adrenal gland insufficiencies
Hypothyreosis
Serious liver disease
Starvation
If you are experiencing one of more symptoms that you suspect is due to low blood sugar levels, the best thing you can do is to immediately eat or drink something rich in glucose or carbohydrates.
There are several symptoms of low blood sugar levels. Which symptoms you will experience may vary, but some of the most common symptoms are:
Hunger
Fatigue
Dizzyness, lightheadedness
Irritation
Increased and/or irregular heart rate
Headaches
Tremor
Affected sight and/or speech
Loss of consciousness
Seizure
Important note: Severe hypoglycemia is dangerous and requires emergency treatment!
What are normal levels of glucose?
Levels of blood glucose can be divided into levels taken on an empty stomach or not.
Empty stomach/fasting:
Low levels
Normal levels
4,0-6,0 mmol/L
High levels
Not on an empty stomach/fasting:
Low levels
Normal levels
-8,7 mmol/L
High levels
If you have increased levels of blood glucose, you might be suffering from diabetes or prediabetes. This is interpreted through the following blood glucose levels:
Prediabetes
Fasting:
6,1-6,9 mmol/L in several tests
Not fasting:
7,8-11,0 mmol/L.
2 hours after a glucose load test 8,9-12,1 mmol/L
Diabetes
Fasting:
7,0 mmol/L or higher more than once taken on different days
Not fasting:
11,1 or higher (12,2 mmol/L or higher from capillary testing)