What Is the Cause of a High Serum Glucose Level on Blood Test?

Doctor discussing results of blood test with patient.

When your doctor orders a serum glucose test he is getting a "spot" check of your body's glucose value at the moment of the draw. Any elevated glucose result should be investigated to see if it is a random occurrence or a warning sign.

Significance

Glucose, like all blood tests, has an established range for normal values. Glucose levels above these values could be indicative of disease. Over a period of time, high glucose levels can cause damage to organs such as kidneys, eyes, heart and nerves.

Expected Glucose Results

A normal fasting serum glucose level should fall between 70 and 110 mg/dL. Random--or non-fasting--values should rise slightly above the fasting level for a normal individual.

Diabetes Mellitus

Diabetes mellitus is the primary cause of elevated serum glucose levels. The American Diabetes Association considers any fasting glucose level above 126 mg/dL, and any "casual" glucose level greater than or equal to 200 mg/dL "abnormally high" or "hyperglycemic."

Other Causes of Elevated Glucose Levels

Other diseases and conditions that can cause elevated serum glucose levels include: stress related to severe trauma or heart attack; chronic renal failure; Cushing's syndrome; certain drugs such as diuretics, birth control pills, and lithium; overeating; and pancreatitis.

Further Testing

An elevated glucose by itself does not automatically indicate diabetes. If your doctor suspects diabetes, she will order additional testing to confirm the diagnosis.

References

• "Tietz Fundamentals of Clinical Chemistry;" Saunders; Sixth Edition 2008
• "Basic Medical Laboratory Techniques;" Delmar; Fourth Edition
• Glucose