Generally, a blood glucose level that reaches 160 milligrams per deciliter is considered to be high, states Joslin Diabetes Center. Blood sugar levels that are greater than the target range set for those diagnosed with diabetes are also regarded as high.
A safe fasting blood sugar level ranges from 70 to 99 mg/dL, notes Virginia Mason Medical Center. After meals, the normal blood glucose level is less than 140 mg/dL. High blood glucose, medically referred to as hyperglycemia, is common among diabetics.
A blood sugar level that persists of more than 180 mg/dL for 3 consecutive days may require adjustments to the diabetic care plan. A reading of 250 mg/dL or higher may indicate the presence of urinary ketones. Patients who are uncertain on how to treat their hyperglycemia are recommended to consult with their health care provider.