In a healthy person, excess sugar leaves the bloodstream within about two hours. This occurs because the pancreas efficiently secretes insulin, which accompanies sugar into cells throughout the body and keeps blood sugar at a normal and stable level.
In an insulin-resistant person, the pancreas produces insulin, but the body does not use it efficiently. Sugar builds up in the bloodstream, resulting in prediabetes or Type 2 diabetes. Causes of Type 2 diabetes include obesity and lack of physical activity. In Type 1 diabetes, the body fails to produce insulin and sugar accumulates in the blood. This type of diabetes is typically diagnosed during childhood.