Diabetes is characterized by the body's inability to metabolize glucose. Hyperglycemia is the condition of excessively high blood glucose levels. Diabetes and hyperglycemia seem like the same medical problem and, according to the American Diabetes Association, all people with diabetes have episodes of hyperglycemia from time to time. Hyperglycemia is often one of the first symptoms to manifest before diabetes is diagnosed.
Causes
According to the Mayo Clinic, there are two primary causes of diabetes: immune system cells begin destroying the pancreatic cells that produce insulin, or the hormone responsible for glucose metabolism; or the body's cells become progressively resistant to the effects of insulin and fail to use circulating sugar from the bloodstream. The first results in type-1 diabetes, while the second condition causes type-2 diabetes.
By contrast, the Mayo Clinic reports that hyperglycemia can occur in people without diabetes who are suffering from severe stress, an infection or sickness or who are recovering from a major surgery or injury. Certain medications can cause hyperglycemia, as well as not exercising enough.
Treatment
While some people with diabetes can successfully control their condition with regular physical activity and a diet high in vegetables, fruits and whole grains and low in fat and sugar, many others -- especially those with type 1 diabetes -- must take insulin and other medications to treat the condition. Severe type-1 diabetes patients may eventually require a pancreatic transplant.
Mild hyperglycemia is usually treated with exercise and less sugar and fat in the diet. However, extreme cases of hyperglycemia are treated with intravenous fluid and electrolyte replacement as well as insulin.
Complications
The complications of severe or untreated diabetic or hyperglycemic conditions also differ. While uncontrolled diabetes can result in hyperglycemia as a short-term complication, kidney damage, nerve damage, heart disease, blindness, osteoporosis and a tendency towards skin infections all occur as long-term complications.
Untreated hyperglycemia can cause similar conditions, but is also connected to the development of diabetic ketoacidosis and diabetic hyperosmolar syndrome. In diabetic ketoacidosis, the body begins to metabolize fat instead of glucose in the absence of insulin; in diabetic hyperosmolar syndrome, unmetabolized glucose builds up in the urine and causes dehydration when it is eliminated from the body. Both conditions can cause comas or death.
