Many people assume that high blood glucose levels occur only in individuals with diabetes. However, there are other more unusual causes of high glucose levels in the blood (also called hyperglycemia).
Primary causes of hyperglycemia do include type I and type II diabetes mellitus. Type I diabetes results solely from lack of insulin secretion due to pancreatic B-cell destruction. Type II diabetes, in contrast, involves an element of insulin resistance. Secondary causes of hyperglycemia result from non-diabetic insulin resistance, toxins, pancreatic diseases and endocrine dysfunction.
Insulin resistance may occur due to obesity, lack of exercise, cirrhosis of the liver, and/or stress. Toxins that can cause elevated blood sugar include alcohol, prescription medications and the metal cadmium. Diseases of the exocrine pancreas that can cause high blood glucose include a hereditary condition called hemochromatosis as well as pancreatic cancer. Several forms of endocrine dysfunction may cause hyperglycemia, including acromegaly, hyperthyroidism, hypercortisolism and pheochromocytomas.
Glucose toxicity is an interesting phenomenon which can contribute to high blood glucose in some individuals. Glucose toxicity is the condition in which initial hyperglycemia, resulting from any cause, may itself cause further high glucose levels by decreasing insulin sensitivity and increasing glucose production in the liver.
High blood glucose can be caused by many conditions other than Type 1 or 2 Diabetes mellitus. However, Type 2 diabetes is the most common cause of hyperglycemia in adults in the United States. A full discussion of the non-diabetic causes of high blood sugar can be found here: http://tiny.ly/oPy9 .