Hyperglycemia or high blood sugar usually only occurs in people who have diabetes mellitus.
When a person eats, food is broken down into various components, one of which is glucose. Glucose enters the bloodstream, where it is taken up by cells which use it as an energy source. This cellular uptake of glucose requires a hormone called insulin, which is produced by the pancreas.
In people with diabetes, the level of insulin produced is either inadequate or the insulin that is produced fails to work properly (insulin resistance). The glucose remains in the blood, which eventually leads to the symptoms of hyperglycemia. The excess glucose in the blood enters the urine and takes water, minerals and salt along with it. This leads to symptoms such as increased thirst, increased urination and eventually the patient may develop dehydration.
Several factors increase the likelihood of hyperglycemia occurring in people with diabetes and examples of these are given below.
Some women develop hyperglycemia as the result of a condition called gestational diabetes which can develop during pregnancy. This form of diabetes develops when the body fails to produce enough insulin to meet the demands of pregnancy, which causes an increased level of glucose in the blood.