A chart that helps patients determine if their blood glucose levels are too high is available at WebMD. What is considered high glucose depends on several factors, such as age and time since last meal. The chart lists target blood glucose levels before meals, after eating and for different ages.
The measurement taken before eating is called fasting blood glucose, according to WebMD. For diabetic adults of all ages, fasting glucose should be 100 milligrams per deciliter, or mg/dL, or lower. The measurement taken within two hours of eating is called postprandial blood glucose. Target postprandial levels range between 140 and 160 mg/dL based on age. Older patients are allowed higher postprandial levels than younger patients.