Symptoms and Signs of High Blood Sugar

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Medically Reviewed on 3/11/2019

Doctor's Notes on High Blood Sugar

Hyperglycemia refers to high levels of glucose (blood sugar) in the blood. It is a characteristic sign of type 1 and type 2 diabetes as well as prediabetes. Diabetes is the most common cause of hyperglycemia. Less common causes can include tumors that secrete hormones, pancreatitis, Cushing’s syndrome, and taking certain medications.

Mild hyperglycemia may not result in any symptoms or signs. When present, the most common associated signs and symptoms are increased thirst (known as polydipsia) and the need to urinate frequently. Other possible symptoms that can accompany hyperglycemia are headaches, increased hunger, blurred vision, tiredness, and problems with concentration. When hyperglycemia is present over the long term, such as in poorly-controlled diabetes, it can cause poor wound healing, nerve damage, vision problems, and damage to the blood vessels and kidneys. 

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Kasper, D.L., et al., eds. Harrison's Principles of Internal Medicine, 19th Ed. United States: McGraw-Hill Education, 2015.