Monitoring Glucose (Blood Sugar) Levels
Both low blood sugar (hypoglycemia) and high blood sugar (hyperglycemia) are of concern for patients who take insulin. It is important, therefore, to carefully monitor blood glucose levels. In general, patients with type 1 diabetes need to take readings four or more times a day. Patients should aim for the following measurements:
- Pre-meal glucose levels of 70 - 130 mg/dL
- Post-meal glucose levels of 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- Using fresh strips; outdated strips may not provide accurate results.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.
Continuous Glucose Monitoring Systems
Continuous glucose monitoring systems (CGMs) use a needle-like sensor inserted under the skin of the abdomen to monitor glucose levels every 5 minutes. Depending on the system, CMGs measure glucose levels for 3- 7 days and sound an alarm if glucose levels are too high or low. These devices are used in addition to traditional fingerstick test kits and glucose meters but do not replace them.
Review Date: 05/05/2011
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.