Postprandial Glucose Test (PPG)

Postprandial Glucose Test (PPG) -Why am I having this test?

You may have a postprandial glucose test (PPG) to:

• Screen for diabetes (diabetes mellitus). More tests may be needed to confirm a diagnosis of diabetes.
• Check how well your diabetes management plan is working, if you are already diagnosed with diabetes. If you have diabetes, you may need to have PPG tests frequently, especially if you:
  • Take more than one medicine and are at risk for high or low blood sugar (glucose).
  • Have a history of high blood glucose after meals.
  • Are a woman who is pregnant and has diabetes or a temporary form of diabetes that develops during pregnancy (gestational diabetes mellitus).
  • Are on a new or changing insulin regimen.

What is being tested?

Your blood glucose level is tested 2 hours after you eat a meal. This provides information about how well your body responds to glucose and starch (carbohydrates) after you eat a meal.

What kind of sample is taken?

A blood sample is required for this test. It is usually collected by inserting a needle into a blood vessel.

How do I prepare for this test?

You will need to eat a meal that includes at least 75 grams of carbohydrate. The meal should include high-carbohydrate foods, such as bread, pasta, potatoes, and other starchy foods.

Two hours after eating this meal, a blood sample is taken. Do not do any of the following until after your blood sample is taken:

• Eat anything else. Eating anything during the testing period can affect test results. You may drink water during the testing period.
• Drink alcohol.
• Smoke.
• Exercise.
• Take any medicines that will affect your blood glucose.

Tell a health care provider about:

• Any allergies you have.
• All medicines you are taking, including vitamins, herbs, eye drops, creams, and over-the-counter medicines.
• Any blood disorders you have.
• Any surgeries you have had.
• Any medical conditions you have.
• Whether you are pregnant or may be pregnant.
• Whether you are unable to finish your meal or drink, or you vomit.

How are the results reported?

Results will be reported as a value that shows how much glucose is in your blood. This may be reported as milligrams per deciliter (mg/dL) or millimoles per liter (mmol/L). Your health care provider will compare your results to normal ranges that were established after testing a large group of people (reference ranges). Reference ranges may vary among labs and hospitals.

For this test, a common reference range is less than 140 mg/dL (7.8 mmol/L). If you have diabetes and you are being tested to see how well your diabetes management plan is working, your reference range is less than 180 mg/dL (10.0 mmol/L).

What do the results mean?

Results within the reference range may mean that you do not have diabetes.

Results higher than your reference range may mean that you have:

• Diabetes.
• Gestational diabetes, if applicable.
• Malnutrition.
• Hyperthyroidism.
• Acute stress response.
• Cushing syndrome.
• Tumors.
• Kidney failure.
• Acromegaly.
• Liver disease.

If you are already diagnosed with diabetes:

• Results within your reference range mean that your diabetes management plan is working well and keeping your blood glucose in the normal range after you eat a meal.
• Results higher than your reference range may mean that your diabetes management plan is not working well. You may need to work with your health care provider to adjust your plan.

Talk with your health care provider about what your results mean.

Questions to ask your health care provider

Ask your health care provider, or the department that is doing the test:

• When will my results be ready?
• How will I get my results?
• What are my treatment options?
• What other tests do I need?
• What are my next steps?

Summary

• The postprandial glucose test (PPG) may be used to screen for diabetes (diabetes mellitus).
• If you are already diagnosed with diabetes, your health care provider may recommend that you have this test to check how well your diabetes management plan is working.
• This test is done to see how well your body responds to glucose and starch (carbohydrates) after you eat a meal.
• Talk with your health care provider about what your results mean.

What research says about Postprandial Glucose Test?

Postprandial blood glucose is a stronger predictor of cardiovascular events than fasting blood glucose in type 2 diabetes mellitus, particularly in women: lessons from the San Luigi Gonzaga Diabetes Study.

In a population of 529 (284 men and 245 women) consecutive type 2 diabetic patients attending our diabetes clinic, we evaluated the relationships, corrected for cardiovascular risk factors and type of treatment, between cardiovascular events in a 5-yr follow-up and baseline values of hemoglobin A1c (HbA1c) and blood glucose measured: 1) after an overnight fast, 2) after breakfast, 3) after lunch, and 4) before dinner. Continuous variables were categorized into tertiles.

Results: We recorded cardiovascular events in 77 subjects: 54 of 284 men (19%) and 23 of 245 women (9.4%). Univariate analysis indicated that cardiovascular events were associated with increasing age, longer diabetes duration, and higher HbA1c and fibrinogen in men, and higher systolic blood pressure, albumin excretion rate, HbA1c, and all blood glucose values in women. Smoking was more frequent in subjects with events. When all blood glucose values and HbA1c were introduced simultaneously in the models, only blood glucose after lunch predicted cardiovascular events, with hazard ratio of the third tertile vs. the first and the second tertiles greater in women (5.54; confidence interval, 1.45-21.20) than in men (2.12; confidence interval, 1.04-4.32; P < 0.01).

Conclusions of this Study: Postprandial, but not fasting, blood glucose is an independent risk factor for cardiovascular events in type 2 diabetes, with a stronger predictive power in women than in men, suggesting that more attention should be paid to postprandial hyperglycemia, particularly in women.