Post prandial glucose (PPBS): normal range

A post prandial glucose test measures how much glucose is in your blood about two hours after eating, when the rise that follows a meal should have settled. MedlinePlus lists the two-hour post prandial test alongside the oral glucose tolerance test, in which you drink a fluid with a set amount of glucose and give a second sample two hours later. Blood glucose normally rises a little after a meal and insulin brings it down.

Doctors order a PP glucose to see how your body handles sugar after food, usually read beside the fasting value from the same morning; Lab Tests Online UK notes that people with diabetes are often tested both fasting and after meals.

The two-hour sample of the oral glucose tolerance test is used to detect type 2 diabetes, prediabetes and diabetes in pregnancy, and NIDDK publishes its cut-offs: 139 mg/dL or below, 140 to 199, and 200 or above. A doctor usually confirms a result in the diabetes band with a second test.

A PP result depends on the meal and the timing as much as on your body.

• The size and content of the meal change the rise: a larger or more carbohydrate-heavy meal pushes glucose higher before it settles.
• Timing matters: the published cut-offs are for a sample taken two hours after the glucose drink, so a sample taken well before or after that mark is not a true two-hour value.
• Stress from illness, injury or surgery can raise blood glucose.
• Medicines such as steroids, some diuretics and some antidepressants can raise glucose; diabetes medicines and insulin lower it.
• Hard exercise before the sample can lower the result.
• Pregnancy changes how glucose is read; NIDDK says some tests use different cut-offs in pregnancy.