Monitoring Glucose (Blood Sugar) Levels
Both low blood sugar (hypoglycemia) and high blood sugar (hyperglycemia) are of concern, especially for patients who take insulin. Blood glucose levels are generally more stable in type 2 diabetes than in type 1, so doctors usually recommend measuring blood levels only once or twice a day. For patients who have become insulin-dependent, more intensive monitoring is necessary. Patients should aim for the following measurements:
- Pre-meal glucose levels of between 70 - 130 mg/dL
- Post-meal glucose levels of between less than 180 mg/dL
Different goals may be required for specific individuals, including pregnant women, very old and very young people, and those with accompanying serious medical conditions.
Finger-Prick Test. A typical blood sugar test includes the following:
- A drop of blood is obtained by pricking the finger.
- The blood is then applied to a chemically treated strip.
- Monitors read and provide results.
Home monitors are about 10 - 15% less accurate than laboratory monitors, and many do not meet the standards of the American Diabetes Association. Most doctors believe, however, that they are accurate enough to indicate when blood sugar is too low.
Some simple procedures may improve accuracy:
- Testing the meter once a month.
- Recalibrating it whenever a new packet of strips is used.
- Using fresh strips; outdated strips may not provide accurate results.
- Keeping the meter clean.
- Periodically comparing the meter results with the results from a laboratory.
For patients who have trouble controlling hypoglycemia (low blood sugar) or fluctuating blood sugar levels, continuous glucose sensor monitors are also available. Continuous glucose sensor monitors do not replace fingerstick glucose meters and test strips, but are used in combination with them. [For more information, see In-Depth Report #9: Diabetes - type 1.]
Review Date: 04/01/2010
Reviewed By: Harvey Simon, MD, Editor-in-Chief, Associate Professor of Medicine, Harvard Medical School; Physician, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.