Does sugar cause large blood sugar fluctuations?

Blood sugar fluctuations after a meal are natural. It is nothing to worry about if you are otherwise healthy. The body regulates itself between meals.

Intake of carbohydrates – including sugar – causes blood sugar to rise. However, there is a difference in how fast the carbohydrates are absorbed into the bloodstream. If a food has a high glycaemic index (GI), the carbohydrates are quickly converted to glucose and absorbed. This results in a rapid increase in blood glucose. Foods with a low GI take longer to be absorbed into the bloodstream. The glycaemic index is a measure of how different types of foods with the same content – normally 50 grams – affect the blood sugar level compared to a reference food, which is normally white bread or glucose.

Sugar (sucrose) is not one of the carbohydrates that produce the largest rise in blood sugar. This is because sugar (sucrose) is a combination of glucose and fructose, in which glucose (which is also called grape sugar) produces a high blood sugar increase while fructose produces a low blood sugar increase (see table below).

Foods with a low GI are considered by some to be healthy because they produce a lower increase in blood sugar. Other people believe it is a good idea to go for a low GI if you want to lose weight; however, these ideas have not been scientifically proven.

It is normal for the blood sugar to fluctuate between narrow limits during the day (between about 4 and 8 mmol/L). It is highest after you have eaten and, generally, lowest when you get up in the morning. Blood sugar fluctuations are natural and nothing to worry about if you are otherwise healthy. The body regulates itself. See the graph below.

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