Knowing your blood glucose after eating is just one way to track your progress in controlling blood sugar.
Your blood sugar naturally rises after you eat. What you eat can influence how high it rises, but generally, if you don't have diabetes, blood sugar after eating -- what your doctor might call postprandial blood glucose levels -- shouldn't rise to more than 200 mg/dl if you check it within two hours after a meal, according to Virginia Mason Medical Center.
When you eat lunch, your body takes whatever you put into it and converts it to energy -- or stores it as fat. Carbohydrates such as bread, pasta and other starches as well as fruits, vegetables and simple sugars break down quickly and absorb into your bloodstream as glucose. From there, insulin released from the pancreas helps cells remove the glucose to use as energy. If you take in more carbohydrate than your body can immediately process, your blood sugar rises temporarily. Normally, your blood sugar two hours after eating remains below 120 mg/dl and won't exceed 140 mg/dl, an April 2002 article published in "Clinical Diabetes" explains.
While knowing your blood sugar a few hours after eating is useful information, because it shows how well you process glucose, your doctor normally won't use this number alone to diagnose you with diabetes. Both your fasting glucose and your glucose levels measured after ingesting a specific amount of glucose after exactly two hours are used to diagnose diabetes. A glucose level of 200 or higher two hours after ingesting a glucose solution, along with a fasting blood glucose of 126 mg/dl or higher on two separate occasions can be used to diagnose diabetes, according to the Virginia Mason Medical Center.
The Influence of Foods
Your body can only absorb simple sugars such as glucose. Complex carbohydrates like those found in starches must break down into easily absorbed forms of glucose, which takes time. If you eat an entire pound of jelly beans, the influx of simple sugar in the form of glucose found in jelly beans makes your blood sugar rise higher quickly. It will rise more slowly if you eat a meal high in whole grains and vegetables, which take longer to break down into simple sugars. For this reason, complex carbohydrates help stabilize your blood sugar levels.
Keeping Blood Sugar Stable
Doctors often prefer to use your hemoglobin A1C levels to monitor your average blood glucose over a three-month period rather than just relying on postprandial and fasting blood sugars. This test measures the percentage of hemoglobin cells coated with glycolated sugar in your bloodstream. A level of 6.5 percent indicates that you have diabetes; 7 percent or less is considered well-controlled diabetes if you've already been diagnosed. An A1C level between 5.7 and 6.4 percent indicates that you have pre-diabetes, which puts you at high risk for developing diabetes in the future. An A1C level of 6 percent correlates with an average blood sugar of 126 mg/dl; 7 percent correlates with an average blood sugar of 154 mg/dl, MayoClinic.com explains.