In healthy people, after eating, food breaks down into blood sugar, or glucose. Insulin, a hormone produced in the pancreas, transports the glucose to cells throughout the body. People with diabetes either make no insulin at all or produce varying amounts, both of which can impair the cells from absorbing glucose to produce energy.
High Blood Sugar
High blood sugar levels could mean that you have diabetes. Your doctor, however, will do several readings to make a definitive diagnosis. A fasting blood glucose level of 126 mg/dL or higher is considered high. On a two-hour oral glucose tolerance test, 200 mg/dL is high. On a random blood glucose test, 200 mg/dL is considered high.
Types of Tests
A fasting blood sugar test, or FBS, measures blood glucose levels when you haven't eaten for eight hours or more. When checking for prediabetes or diabetes, this is the first test your doctor conducts. A two-hour postprandial blood sugar test measures glucose levels two hours after eating. A random blood sugar test, or RBS, measures blood glucose at any time, regardless of when you last ate. This test can be administered several times throughout the day and is useful for people who do not have diabetes because their blood sugar levels should not fluctuate. If you have not been diagnosed with diabetes and produce varying results on an RBS, it could indicate a problem.
Hyperglycemia
Hyperglycemia, also known as high blood sugar, can occur when the body does not have enough insulin or cannot use insulin properly. If you have diabetes, it can occur if you do not give yourself enough insulin or if the insulin isn't effective. It can also occur from eating too much, not getting enough exercise, or if you are ill or overstressed.
Symptoms
While a blood glucose test will chart your blood sugar levels, you will probably be aware that you're severely hyperglycemic by the signs and symptoms. Hyperglycemia can cause shortness of breath, nausea, vomiting and dry mouth. You may start urinating frequently and feel extremely thirsty. If it goes untreated, you could go into a diabetic coma, known as ketoacidosis, which is a life-threatening condition.
References
- National Diabetes Information Clearinghouse: National Diabetes Statistics 2011
- Virginia Madison Medical Center: What are Normal Blood Glucose Levels?
- American Diabetes Association: Hyperglycemia
- National Diabetes Information Clearinghouse: Am I at Risk for Type 2 Diabetes: November 2008
- American Diabetes Association: Checking Your Blood Glucose
