When you have an excess of glucose in your blood stream which would also imply that you have extra blood sugar in your blood stream, you can be definite that you suffer from diabetes. Sugar in your blood is an essential as it serves as the source of energy for your body but again too much of it is not very healthy. Glucose does not only come from the food you eat but is also produced by your liver and muscles while the blood helps to carry all the glucose to the various cells in the body. Insulin is also another chemical produced by the pancreas that helps to moderate the levels of glucose in your body by helping the glucose to get absorbed by the cells. So if your insulin fails to work efficiently, the glucose would stay back in your blood and cause your level of glucose to rise causing either pre diabetes or diabetes.