The ideal blood sugar level varies from person to person and can depend on a variety of factors, including how long it has been since a person has had a meal. In general, levels ranging between 70 to 100 mg/dL (milligrams per deciliter) are considered normal for non-diabetics who have not just had a meal. If a person has just had a meal, the ideal level of blood glucose should be between 70 and 145 mg/dL for non-diabetics. Levels that are higher than this could indicate diabetes or pre-diabetes.
A person who consistently has blood sugar levels that range from 100 to 125 mg/dL after an eight-hour fast may have pre-diabetes. Levels of 140 to 199 mg/dL after eating or following an oral glucose test also indicate pre-diabetes. A person who is diagnosed with pre-diabetes is at great risk of developing type 2 diabetes and should immediately start taking steps to prevent it by making certain lifestyle changes, such as improved eating habits and exercise. These changes may additionally help a person to lose weight, which would be beneficial for someone who is overweight and at risk of developing type 2 diabetes.
Blood sugar levels that exceed 125 mg/dL after an eight-hour fast indicate diabetes. If levels exceed 200 mg/dL after an oral glucose test, it is also likely that diabetes is present. The ideal blood sugar level for diabetics is higher than the normal level for non-diabetics. People with diabetes whose levels are between 80 and 120 mg/dL after fasting or just before eating are thought to have their blood sugar under control. The ideal blood sugar level for diabetics just after meals should not typically exceed 160 mg/dL.
Doctors do not typically diagnose diabetes until several tests have been administered. It is important for doctors to be sure that blood sugar levels are staying consistently high before they make a firm diagnosis. This is usually done by using both fasting blood sugar tests and oral glucose tests. With a fasting test, a person's blood sugar levels are checked either first thing in the morning or just after an eight-hour fast. An oral glucose test is a test doctors use to see how high a person's blood sugar level rises after drinking a very sweet, sugary drink and then checking the levels again a few hours later to see how much they drop. These tests are usually done a few different times on different days so that doctors can be certain a person is testing well above the ideal blood sugar level before confirming diabetes.