usually 283 is high sugar level,its not dangerous in 2hrs but long standing high sugar can causehigh blood sugar levels, a condition called hyperglycemia. Over a long period of time, hyperglycemia damages the retina of the eye, the kidneys, the nerves, and the blood vessels. Damage to the retina from diabetes (diabetic retinopathy) is a leading cause of blindness. Damage to the kidneys from diabetes (diabetic nephropathy) is a leading cause of kidney failure. Damage to the nerves from diabetes (diabetic neuropathy) is a leading cause of foot wounds and ulcers, which frequently lead to foot and leg amputations. Damage to the nerves in the autonomic nervous system can lead to paralysis of the stomach (gastroparesis), chronic diarrhea, and an inability to control heart rate and blood pressure during postural changes. Diabetes accelerates atherosclerosis, (the formation of fatty plaques inside the arteries), which can lead to blockages or a clot (thrombus). Such changes can then lead to heart attack, stroke, and decreased circulation in the arms and legs (peripheral vascular disease). Diabetes predisposes people to high blood pressure and high cholesterol and triglyceride levels. These conditions independently and together with hyperglycemia increase the risk of heart disease, kidney disease, and other blood vessel complications. In the short run, diabetes can contribute to a number of acute (short-lived) medical problems. Many infections are associated with diabetes, and infections are frequently more dangerous in someone with diabetes because the body s normal ability to fight infections is impaired. To compound the problem, infections may worsen glucose control, which further delays recovery from infection.