What is blood sugar (glucose)?

From a chemical point of view, glucose is a simple sugar. This means that it is not linked to other sugar molecules. For this reason, glucose enters the bloodstream directly, without first being broken down by digestive enzymes.

Glucose is an important energy supplier for our body cells, especially for the nerve cells. The hormone insulin is necessary for its transport into the cells. This is produced by the pancreas. Only nerve cells and red blood cells do not need insulin to absorb glucose.  

The glucose level should be measured especially when there is an acute suspicion of diabetes. Type 1 diabetes can develop within a few days to weeks and causes symptoms such as frequent urination, severe thirst, fatigue, weight loss or general listlessness.

When fasting, the glucose level in the blood of people without diabetes is less than 100 milligrams per decilitre or, in other words, less than 5.6 millimoles per litre. After eating, the blood glucose level usually rises somewhat, but not above 140 milligrams per decilitre.

Only when the blood glucose level exceeds 126 milligrams per decilitre when fasting or 200 milligrams after eating is it called diabetes mellitus.

Values between 100 and 125 mg/dl in the fasting state can already indicate a preliminary stage of type 2 diabetes. The final diagnosis can be clarified with a so-called glucose tolerance test (OGTT).