Everything you need to know about blood sugar levels
What is blood sugar/glucose?
Blood sugar, also known as blood glucose, is your body’s main energy source. Your bloodstream carries glucose (a simple sugar) to all of the cells in your body, allowing it to function correctly. We get glucose from the food we eat. Blood glucose measurements represent how much sugar is being transported in your bloodstream at the time of the measurement.
Your body regulates its blood sugar levels to keep them at a healthy level as the blood’s internal environment has to remain stable in order for the body to function optimally. This vital balance is known as homeostasis.
The word glucose is derived from the Greek word meaning 'sweet'. Glucose, found in carbohydrate-rich foods such as potatoes, fruit and bread, travels down the oesophagus and to the stomach. Once food is in the stomach, enzymes and acids will break it down into small pieces. Glucose will be absorbed from the small intestine into the bloodstream in order for it to be transported throughout the body.
Blood sugar levels fluctuate throughout the day, rising after you have eaten and then settling again after an hour or so. These levels are their lowest before your first meal of the day, which is typically breakfast.
How does the body control blood sugar?
When your blood sugar levels rise, as they do after eating a meal, the pancreas releases insulin1. Insulin enters the bloodstream in order to ensure that the sugar from food is transported by the blood to the cells where it is required, and transformed into energy that allows the body to function.
Insulin travels to different target cells within the liver and muscle tissues of the body, causing glucose to be absorbed and used for energy. In the liver it is converted into glycogen. Glycogen is a readily mobilised form of stored glucose when the body needs it.
If your blood glucose reaches a low level when you haven’t eaten for some time and no nutrients from your last meal remain in circulation in the body, then your pancreas will produce a different hormone known as glucagon. This hormone will cause the liver to convert the stored glycogen back into glucose and release this into the blood. Thus, bringing your blood sugar levels back to normal.
Insulin, glycogen and glucagon levels will continually rise and fall in order to regulate your blood sugar levels. This process is a simple one of negative feedback, meaning if one of the components responsible for regulating blood sugar deviates too much, then the body will attempt to correct it.
What is diabetes mellitus?
Diabetes mellitus is a condition wherein the body either does not make enough of the hormone insulin or it does not utilise the hormone efficiently. This results in an accumulation of glucose in the blood.
Diabetes is a chronic disorder that, if not treated and managed carefully, can result in severe health complications that include blindness, heart disease and even lower-extremity amputations.
If you suffer from type 1 diabetes then your immune system will destroy the cells that release insulin, eventually eliminating the production of this vital hormone in the body. If your body does not produce insulin, then your cells are unable to absorb the sugar needed for energy.
Suffering from type 2 diabetes means that your body is unable to use the insulin it produces efficiently, insulin resistance is the early onset of Type 2 Diabetes. The fat, liver and muscle cells of the body are unable to absorb and store glucose leading to a build-up in the blood known as hyperglycaemia which impairs a variety of bodily functions.
1. PubMed Health. Blood Glucose. Available: https://www.ncbi.nlm.nih.gov/pubmedhealth/PMHT0024697/ [Accessed 03.10.2017]
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