Hyperglycemia or Hyperglycæmia, or high blood sugar, is a condition in which an excessive amount of glucose circulates in theblood plasma. This is generally a glucose level higher than (200 mg/dl). Reference ranges for blood tests are 11.1 mmol/l, but symptoms may not start to become noticeable until even higher values such as 250–300 mg/dl or 15–20 mmol/l. A subject with a consistent range above 126 mg/dl or 7 mmol/l is generally held to have hyperglycemia. Chronic levels exceeding 7 mmol/l (125 mg/dl) can produce organ damage.