Understanding Blood Sugar

Blood sugar, or blood glucose, is the sugar that the bloodstream carries to all the cells in the body to supply energy. The sugar comes from the food we eat. The human body regulates blood glucose levels so that they are neither too high nor too low. The blood’s internal environment must remain stable for the body to function.

The sugar in the blood is not the same as sucrose like the sugar we take with our food. There are different kinds of sugars. Sugar in the blood is known as glucose.
The digestive system breaks down carbohydrates from food into various sugar molecules. One of these sugars is glucose, the body’s main source of energy. The glucose goes straight from the digestive system into the bloodstream after food is consumed and digested.

But glucose can only enter cells if there is insulin in the bloodstream too. Without insulin, the cells will not receive the required glucose even though there might be glucose in the blood.


After we eat, blood sugar concentrations rise. The pancreas releases insulin automatically so that the glucose enters cells. As more and more cells receive glucose, blood sugar levels return to normal again.

Blood sugar or blood glucose levels represent the amount of sugar being transported in the blood during any instant. Blood glucose levels change throughout the day. They are at their lowest point before the first meal of the day, which is normally breakfast.

Normal Blood Glucose Levels

Fasting (Before breakfast)

  1. For someone without diabetes: 3.9 to 5.6 mmol/L
  2. For someone with prediabetes: 5.6 to 6.9 mmol/L
  3. For someone with diabetes:       4.4 to 7.2 mmol/L

2 hours after meal

  1. For someone without diabetes: Less than 7.8 mmol/L
  2. For someone with prediabetes: Less than 11.0 mmol/L
  3. For someone with diabetes:       Less than 11.0 mmol/L

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