context: Blood sugar control is at the center of any diabetes treatment plan. High blood sugar, or hyperglycemia, is a major concern, and can affect people with both type 1 and type 2 diabetes . There are two main kinds: Fasting hyperglycemia. This is blood sugar that's higher than 130 mg/d L (milligrams per deciliter) after not eating or drinking for at least 8 hours. Postprandial or after-meal hyperglycemia. This is blood sugar that's higher than 180 mg/d L 2 hours after you eat. People without diabetes rarely have blood sugar levels over 140 mg/d L after a meal, unless it's really large. Frequent or ongoing high blood sugar can cause damage to your nerves, blood vessels, and organs. It can also lead to other serious conditions. People with type 1 diabetes are prone to a build-up of acids in the blood called ketoacidosis. If you have type 2 diabetes or if you're at risk for it, extremely high blood sugar can lead to a potentially deadly condition in which your body can't process sugar. It's called hyperglycemic hyperosmolar nonketotic syndrome ( HHNS). You'll pee more often at first, and then less often later on, but your urine may become dark and you could get severely dehydrated. It's important to treat symptoms of high blood sugar right away to help prevent complications. Your blood sugar may rise if you: Skip or forget your insulin or oral glucose-lowering medicine Eat too many grams of carbohydrates for the amount of insulin you took, or eat too many carbs in general Have an infection Are ill Are under stress Become inactive or exercise less than usual Take part in strenuous physical activity, especially when your blood sugar levels are high and insulin levels are low Early signs include: Increased thirst Headaches Trouble concentrating Blurred vision Frequent peeing Fatigue (weak, tired feeling) Weight loss Blood sugar more than 180 mg/d L Ongoing high blood sugar may cause: Vaginal and skin infections Slow-healing cuts and sores Worse vision Nerve damage causing painful cold or insensitive feet, loss of hair on the lower extremities, or erectile dysfunction Stomach and intestinal problems such as chronic constipation or diarrhea Damage to your eyes, blood vessels, or kidneys If you have diabetes and notice any of the early signs of high blood sugar, test your blood sugar and call the doctor. He may ask you for the results of several readings. He could recommend the following changes: Drink more water. H20 helps remove excess sugar from your blood through urine, and it helps you avoid dehydration. Exercise more. Working out can help lower your blood sugar. But under certain conditions, it can make blood sugar go even higher. Ask your doctor what kind of exercise is right for you. Caution: If you have type 1 diabetes and your blood sugar is high, you need to check your urine for ketones. When you have ketones, do NOT exercise. If you have type 2 diabetes and your blood sugar is high, you must also be sure that you have no ketones in your urine and that you are well-hydrated. Then your doctor might give you the OK to exercise with caution as long as you feel up to it. Change your eating habits. You may need to meet with a dietitian to change the amount and types of foods you eat. Switch medications. Your doctor may change the amount, timing, or type of diabetes medications you take. Don't make changes without talking to him first. If you have type 1 diabetes and your blood sugar is more than 250 mg/d L, your doctor may want you to test your urine or blood for ketones. Call your doctor if your blood sugar is running higher than your treatment goals. If you work to keep your blood sugar under control -- follow your meal plan, exercise program, and medicine schedule -- you shouldn't have to worry about hyperglycemia. You can also: Know your diet -- count the total amounts of carbs in each meal and snack. Test your blood sugar regularly. Tell your doctor if you have repeated abnormal blood sugar readings. Wear medical identification to let people know you have diabetes in case of an emergency.