Blood sugar, or glucose, is the main sugar found in blood. The body gets glucose from the food we eat. This sugar is an important source of energy and provides nutrients to the body's organs, muscles and nervous system. The absorption, storage and production of glucose is regulated constantly by complex processes involving the small intestine, liver and pancreas.
Glucose enters the bloodstream after a person has eaten carbohydrates. The endocrine system helps keep the bloodstream's glucose levels in check using the pancreas. This organ produces the hormone insulin, releasing it after a person consumes protein or carbohydrates. The insulin sends excess glucose in the liver as glycogen.
The pancreas also produces a hormone called glucagon, which does the opposite of insulin, raising blood sugar levels when needed. According to the Johns Hopkins University Sol Goldman Pancreatic Cancer Research Center, the two hormones work together to keep glucose balanced.
When the body needs more sugar in the blood, the glucagon signals the liver to turn the glycogen back into glucose and release it into the bloodstream. This process is called glycogenolysis.
When there isn't enough sugar to go around, the liver hoards the resource for the parts of the body that need it, including the brain, red blood cells and parts of the kidney. For the rest of the body, the liver makes ketones , which breaks down fat to use as fuel. The process of turning fat into ketones is called ketogenesis. The liver can also make sugar out of other things in the body, like amino acids, waste products and fat byproducts, according to the University of California.
Glucose vs. dextrose
Dextrose is also a sugar. It's chemically identical to glucose but is made from corn and rice, according to Healthline. It is often used as a sweetener in baking products and in processed foods. Dextrose also has medicinal purposes. It is dissolved in solutions that are given intravenously to increase a person's blood sugar levels.
Normal blood sugar
For most people, 80 to 99 milligrams of sugar per deciliter before a meal and 80 to 140 mg/dl after a meal is normal. The American Diabetes Association says that most nonpregnant adults with diabetes should have 80 to 130 mg/dl before a meal and less than 180 mg/dl at 1 to 2 hours after beginning the meal.
These variations in blood-sugar levels, both before and after meals, reflect the way that the body absorbs and stores glucose. After you eat, your body breaks down the carbohydrates in food into smaller parts, including glucose, which the small intestine can absorb.
Diabetes happens when the body lacks insulin or because the body is not working effectively, according to Dr. Jennifer Loh, chief of the department of endocrinology for Kaiser Permanente in Hawaii. The disorder can be linked to many causes, including obesity, diet and family history, said Dr. Alyson Myers of Northwell Health in New York.
"To diagnose diabetes, we do an oral glucose-tolerance test with fasting," Myers said.
Cells may develop a tolerance to insulin, making it necessary for the pancreas to produce and release more insulin to lower your blood sugar levels by the required amount. Eventually, the body can fail to produce enough insulin to keep up with the sugar coming into the body.
It can take decades to diagnose high blood-sugar levels, though. This may happen because the pancreas is so good at its job that a doctor can continue to get normal blood-glucose readings while insulin tolerance continues to increase, said Joy Stephenson-Laws, founder of Proactive Health Labs (pH Labs), a nonprofit that provides health care education and tools. She also wrote "Minerals – The Forgotten Nutrient: Your Secret Weapon for Getting and Staying Healthy" (Proactive Health Labs, 2016).
Health professionals can check blood sugar levels with an A1C test, which is a blood test for type 2 diabetes and prediabetes, according to the U.S. National Library of Medicine. This test measures your average blood glucose, or blood sugar, level over the previous three months.
Doctors may use the A1C alone or in combination with other diabetes tests to make a diagnosis. They also use the A1C to see how well you are managing your diabetes. This test is different from the blood sugar checks that people with diabetes do for themselves every day.
In the condition called hypoglycemia, the body fails to produce enough sugar. People with this disorder need treatment when blood sugar drops to 70 mg/dL or below. According to the Mayo Clinic, symptoms of hypoglycemia can be:
- Tingling sensation around the mouth
- An irregular heart rhythm
- Pale skin
- Crying out during sleep
Keeping blood sugar in control
Stephenson-Laws said healthy individuals can keep their blood sugar at the appropriate levels using the following methods:
Maintaining a healthy weight
Talk with a competent health care professional about what an ideal weight for you should be before starting any kind of weight loss program.
Look for and select whole, unprocessed foods, like fruits and vegetables, instead of highly processed or prepared foods. Foods that have a lot of simple carbohydrates, like cookies and crackers, that your body can digest quickly tend to spike insulin levels and put additional stress on the pancreas. Also, avoid saturated fats and instead opt for unsaturated fats and high-fiber foods. Consider adding nuts, vegetables, herbs and spices to your diet.
A brisk walk for 30 minutes a day can greatly reduce blood sugar levels and increase insulin sensitivity.
Getting mineral levels checked
Research also shows that magnesium plays a vital role in helping insulin do its job. So, in addition to the other health benefits it provides, an adequate magnesium level can also reduce the chances of becoming insulin-tolerant.
Get insulin levels checked
Many doctors simply test for blood sugar and perform an A1C test, which primarily detects prediabetes or type 2 diabetes. Make sure you also get insulin checks.
Live Science newsletter
Stay up to date on the latest science news by signing up for our Essentials newsletter.
Live Science Contributor
Alina Bradford is a contributing writer for Live Science. Over the past 16 years, Alina has covered everything from Ebola to androids while writing health, science and tech articles for major publications. She has multiple health, safety and lifesaving certifications from Oklahoma State University. Alina's goal in life is to try as many experiences as possible. To date, she has been a volunteer firefighter, a dispatcher, substitute teacher, artist, janitor, children's book author, pizza maker, event coordinator and much more.
More about heart circulation