Your body maintains tight control on your blood sugar level. An increase normally occurs after meals as sugars and starches break down in your intestines and enter your bloodstream. The magnitude of rise in your blood sugar level after meals varies, depending largely on the nutritional content and volume of the meal. The elapsed time since eating also affects your blood sugar level. Because of the many sources of variability, there is no established normal range for blood sugar among nondiabetic adults after meals.
Rule of Thumb
Although there is no established normal range for blood sugar among nondiabetics after eating, Christopher Grainger Parkin, M.S., reports in an April 2002 article published in "Clinical Diabetes" that glucose values two hours after eating are typically less than 120 mg/dL and rarely greater than 140 mg/dL. A value greater than 140 mg/dL may raise suspicion that your body is not metabolizing glucose normally, prompting additional testing.
Standardized Blood Sugar Tests
If your doctor wants to evaluate you for diabetes or prediabetes, standardized blood glucose tests are performed that eliminate food-related variation. For a fasting blood sugar test, your blood is collected after an overnight fast of at least eight hours. In a nondiabetic, fasting blood glucose should be less than 126 mg/dL. To evaluate how your body manages a dietary glucose load, your doctor may order an oral glucose tolerance test, or OGTT. After an overnight fast, you drink a solution that contains exactly 75 g of glucose. If you do not have diabetes or prediabetes, your blood glucose two hours after drinking the sugar solution should be less than 140 mg/dL.
Random Glucose
A random glucose describes a blood sugar test taken arbitrarily without regard to your last meal. A random blood glucose value of 200 mg/dL or higher strongly suggests the possibility of diabetes. Your doctor will confirm whether you have diabetes with a fasting blood sugar test, OGTT or another test called a hemoglobin A1c.
Emerging Research
Most research on blood sugar levels involves patients with diabetes and prediabetes. The normal variation in blood sugar levels among nondiabetics historically received little attention in the biomedical research community. With growing numbers of people developing type 2 diabetes, however, attention has turned to this topic with some surprising results. In an April 2010 article published in "Diabetologia," Dr. Rikke Borg and colleagues report that blood sugar levels after meals increase to a much greater extent than previously recognized among some nondiabetics. Among the 80 participants in the Borg study, 93 percent experienced blood glucose values greater than 140 mg/dL and 9 percent had values greater than 200 mg/dL. Ongoing research will help doctors determine whether these blood sugar level excursions can help identify nondiabetics at increased risk of developing type 2 diabetes.
References
- "Clinical Diabetes"; Is Postprandial Glucose Control Important? Is It Practical In Primary Care Settings?; Christopher Grainger Parkin, M.S., et al.; April 2002
- "Diabetes Care"; Diagnosis and Classification of Diabetes Mellitus; American Diabetes Association; January 2011
- "Endocrine Practice"; American Association of Clinical Endocrinologists Medical Guidelines for Clinical Practice for Developing a Diabetes Mellitus Comprehensive Care Plan; Yehuda Handelsman, M.D., et al.; March--April 2011
- "Diabetologia"; Real-Life Glycaemic Profiles in Non-Diabetic Individuals with Low Fasting Glucose and Normal Hba1c: The A1C-Derived Average Glucose (ADAG) Study; Rikke Borg, M.D.; April 2010
