Getting Smart About Blood Glucose Testing
To get the most out of monitoring, know when to test and how to act on the results
By David Price, M.D.
When it comes to diabetes, the maxim "knowledge is power" has never been truer. Yet as a physician, I'm surprised by the number of people who aren't adequately trained to use this important diabetes management tool.
Although testing by itself has no direct impact on blood glucose, it does allow you and your health care team to see how well your treatment program is working and it guides treatment changes.
To get the most out of blood glucose testing, you need to know when to test and how to act on the results to minimize your highs and lows, keeping you in range.
How often you test will depend on your level of control, therapy type, and how much your blood sugar fluctuates throughout the day.
Are you in control?
Long-term diabetes control is measured through an A1C test. This lab test shows your average level of control over the past 60-90 days. To reduce the risk of complications, the American Association of Clinical Endocrinologists (AACE) recommends an A1C value of 6.5 percent or less for most people. Today, nearly two thirds of people with type 2 diabetes have blood glucose levels that are out of control. By knowing your A1C level, you and your doctor can personalize a self-monitoring regimen to improve or maintain your control.
Therapy type:
- Insulin (alone or with pills)—Test 3-4 times a day. Insulin can have an immediate and dramatic impact on lowering blood sugar so it's important to test prior to injections to prevent low and high blood sugars.
- Diabetes Pills—While most pills don't lower blood sugar as rapidly as insulin, people who don't require insulin injections are still subject to significant fluctuations (related primarily to food) that require monitoring. If your A1C level is 6.5 percent or greater, test 2-4 times per day. If your blood sugar is well controlled you can test less often, perhaps once a day or less. If you test less frequently, test at a different time each day to give you an early warning if control starts to slip. Include some tests after eating to learn how meals affect you.
- Diet/Exercise Only—Testing can help you understand how new foods or changes in activity will affect blood sugar levels. If you are in control, test daily or a few times each week at different times to make sure your levels are staying in range.
When to test
Deciding when to test depends on discovering when and why your blood sugar goes out of range. Here are some places to start:
- When you wake up. A fasting blood sugar test tells you how well your medications have been working overnight, whether you may be eating too much for dinner, or if you need to adjust a bedtime snack. For most people, your level should be between 80-120 mg/dL.
- Before a meal. Testing before each meal can help you decide what and how much to eat, and, in some cases, how to adjust your medication. You should typically aim for less than 110 mg/dL.
- Two hours after a meal. You'll learn whether you ate too many carbohydrates or if you should cut back or substitute different foods next time. Your goal should be less than 140 mg/dL.
- Exercise. Exercise usually uses up blood glucose, so it makes sense to test before, during and two hours after exercise. If your result is less than 100 mg/dL, eat at least one carbohydrate of choice (for example, a glass of milk) before exercising. However, your glucose may rise if you exercise when you are above 250 mg/dL.
- Bedtime. Your last chance of the day to adjust diet or medication so that you can stay in range during the night.
- Other times to test. Consider additional short-term testing if you feel the signs of hypoglycemia (low blood sugar), illness, changes in physical activity or nutrition, stress resulting from a major life change, worsening A1C results, and changes or adjustments in medication (including a number of medications not related to diabetes treatment).
No one should expect to test their blood glucose at each of these times every day. Instead, smart testing will uncover your biggest opportunities for improvement. For example, if your blood glucose is highest after breakfast, test before and after breakfast until you come up with satisfying menu options that don't raise your blood sugar. Once you've mastered this challenge, reduce (not eliminate) testing around breakfast and focus on your next opportunity for improvement.
Once you understand how your actions directly impact blood glucose levels, you'll be able to make informed choices that will put you in control of your diabetes—that's what I call "testing smart."
David Price, M.D., is the medical director at LifeScan, Inc.
