High blood glucose levels are generally above 160 milligrams per deciliter or above a particular blood glucose target determined by a doctor based on a patient's overall health, states Joslin Diabetes Center. Frequent high blood sugar levels increase the risk of stroke, heart attack, kidney disease, eye disease and other complications.
The fasting plasma blood glucose levels of individuals without diabetes are usually below 100 milligrams per deciliter, notes Joslin Diabetes Center. Doctors may modify the treatment plan of a person with sugar levels above 180 milligrams per deciliter for three consecutive days, as short-term high blood glucose also involves risk of health problems.
Inadequate or improper intake of diabetes pills or insulin, insufficient physical activity, excessive food consumption, or spoiled insulin are potential causes of high blood glucose, according to Joslin Diabetes Center. Inaccurate blood glucose meter readings, stress, injury, surgery and sickness can also raise a person's sugar levels. People with high blood glucose typically feel more thirsty than usual, urinate more frequently, or experience dry mouth or skin.
It helps to drink at least eight glasses of water daily, take immediate action to address high blood glucose levels, and consult a doctor promptly, recommends Joslin Diabetes Center. Diabetics who are taking insulin with blood glucose levels above 250 millimeters per deciliter should check their urine for ketones.