How Is Glucose Absorbed?

Your body can break down fats and even proteins to get the energy it needs. But it's glucose, derived from the digestion of carbohydrates, that your body desires. Glucose is the main source of energy for every single cell, and it is the preferred energy type for brain cells. If you have diabetes, your body has problems handling glucose, which can be very dangerous for your health.

A doctor measures blood sugar levels with a glucose meter (Image: verve231/iStock/Getty Images)

Glucose Conversion

All carbohydrates, with the exception of fiber, eventually wind up as glucose. However, the way they get there varies. Sugars, which are simple carbs, are very small molecules that convert into glucose quickly after combining with enzymes in your small intestine. Starches, which are complex carbohydrates, undergo numerous steps before glucose is formed. When you chew, your mouth secretes saliva, an enzyme that starts breaking down complex starch compounds. Saliva turns starches into a kind of simple carbohydrate. As the simple molecules approach your small intestine, the enzymes there kick in again to break them down further, converting them into glucose.

Glucose Absorption

Your intestinal tract is lined with numerous microvilli, which are tiny fingerlike protrusions that increase surface area for the maximum absorption of nutrients. These microvilli absorb glucose molecules and send them straight into your bloodstream. Once your brain senses that glucose is present, it sends signals to your pancreas to secrete the hormone insulin. Insulin is like a gatekeeper, opening up cell walls and allowing glucose to enter. Whatever glucose isn't needed right away gets converted into glycogen, a polysaccharide that is stored in your liver and muscles as a backup source of energy.

Problems with Glucose Absorption

If you have diabetes, your body doesn't regulate glucose levels well because it has a problem with insulin. With Type 1 diabetes, your body doesn't make enough insulin, and you have to give yourself regular insulin injections to normalize glucose levels. If you have Type 2 diabetes, your body might have plenty of insulin, but your system doesn't use it the way it should. With this form of diabetes, you may have to use prescription medications, take insulin and lose weight to keep your glucose levels stable.

When You Can’t Control Glucose

Your body relies on a steady supply of glucose, and when your body doesn't produce enough insulin or use it properly, your glucose levels can get dangerously out of control. Hypoglycemia, or low blood glucose, leads to dizziness, fatigue, blurred vision, headaches and increased hunger. If your glucose runs high, you could feel overly tired and have vision problems. You'll also most likely be extremely thirsty and have dry mouth no matter how much you drink. Either way, symptoms can be life threatening if left untreated.

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