If you are like most people with diabetes, you test your blood glucose before breakfast. For many people this fasting test is the only one all day.
How long after a meal should you test?
Now, however, the doctors have begun to tell us that we should also do something they call a "postprandial" blood glucose test. Indeed, recent studies show that better control of your postprandial levels--which means after meals--contributes more to improvement in your A1c level than fasting glycemic control. And it is the A1c that is the gold standard for determining glycemic control among people with both type 1 and type 2 diabetes.
But how long after a meal should you test? And do you start counting from when you start eating or when you finish?
A lot of people with diabetes are confused about this. But it is for questions like these that the American Diabetes Association and other organizations have developed guidelines, position papers, and consensus statements.
The American Diabetes Association's Consensus Statement on Postprandial Blood Glucose concludes that generally we should test two hours after the start of a meal (and women with gestational diabetes or pregnancy complicated by diabetes could benefit from testing after one hour). Testing two hours "after the start of a meal is practical, generally approximates the peak value in patients with diabetes, and provides a reasonable assessment of postprandial hyperglycemia."
Because of this, we should shoot for a target level of under 140 two hours after eating, says the American College of Endocrinology Consensus Development Conference on Guidelines for Glycemic Control. This panel says that people who don't have diabetes generally peak about an hour after the start of a meal and rarely exceed 140 mg/dl.
While some people still prefer to test one hour after starting a meal, most prefer to follow the guidelines. The best thinking in my view came from Helen, who wrote on a diabetes mailing list, "If I aim for pre-meal levels to occur an hour after eating, I chance going low two hours postprandial and for sure three hours postprandial. My blood glucose level tends to decline from hour two to hour three. Therefore I do not test one hour postprandial—there is nothing I would do with that information other than aggravate myself."
The ADA's Consensus Statement on Postprandial Blood Glucose is one of 12 that its directory of Consensus Statements lists. But only the four most recent are online.
The three others are:
The ADA also lists 28 technical reviews. But only the eight most recent are available in full text online.
These online technical reviews are:
- An Economic
Analysis of Interventions for Diabetes,
- Management of
Hyperglycemic Crises in Patients With Diabetes
- The Treatment
of Hypertension in Adult Patients With Diabetes
- Use of Influenza
and Pneumococcal Vaccines in People With Diabetes
Nutrition Principles and Recommendations for the Treatment and Prevention of
Diabetes and Related Complications
- Pancreas and
Islet Transplantation for Patients With Diabetes
- Screening for
Type 2 Diabetes, and
- Smoking and Diabetes.
Even more important, however, are the ADA's Position Statements. In 32 separate statements they cover everything from standards of medical care to unproven therapies.
You can also find online the Summary of Revisions for the 2002 Clinical Practice Recommendations, Report of the Expert Committee on the Diagnosis and Classification of Diabetes Mellitus, and National Standards for Diabetes Self-Management Education.
The American Diabetes Association originally published this article on its Web site as one of my “About the Internet” columns.
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