Glucose monitoring is a method of self-testing glucose (blood sugar) levels for the management of diabetes. It involves pricking the finger or an alternate site such as the arm or thigh for a sample of blood and placing that sample on a test strip. A glucose meter then analyzes the strip. The meter digitally displays the glucose level as a number in milligrams per deciliter (mg/dL).

Other methods of glucose monitoring exist, including visually read blood and urine strips and home glycohemoglobin tests. However, the glucose meter is considered the most accurate tool for measuring day-to-day glucose control at home.

People with diabetes should work to keep their glucose levels as close to normal as possible to feel their best and to avoid glucose irregularities such as hyperglycemia, hypoglycemia, insulin shock and unstable diabetes. Controlling glucose can prevent or delay the development of immediate complications such as unconsciousness and long-term complications such as diseases of the eyes, kidneys, nerves and blood vessels. People with diabetes can control their glucose with methods that may include diet, exercise, insulin and anti-diabetic agents, as prescribed by their physician.

Self-monitoring of blood glucose allows patients to record test results and, according to their physician-prescribed treatment plan, make healthy decisions about diet, exercise and medication dosage. Monitoring glucose provides important knowledge for the management of diabetes. Without monitoring, the patient is not informed of the balance between levels of insulin and glucose. People with diabetes and their physicians can examine patterns in glucose test results and judge if the diabetes management plan is working, or if changes need to be made.

All people with diabetes can benefit from glucose monitoring. It is especially important for diabetic patients who are:

• Taking insulin or other diabetes medications
• Pregnant
• Having difficulty controlling glucose
• Having ketones in urine from high blood glucose
• Having low glucose without the normal warning signs (hypoglycemia unawareness)
• Experiencing an illness

Steps to effective glucose monitoring include:

• Know the target glucose range. For people with diabetes, the American Diabetes Association (ADA) recommends a glucose range of 80 to 120 mg/dL before meals and 100 to 140 mg/dL at bedtime for whole blood readings and 90 to 130 mg/dL before meals and 110 to 150 mg/dL at bedtime for plasma blood readings.
  
  
  However, this range is not appropriate for everyone. The target glucose range is a personalized number given by a physician. It is usually based on factors such as age, level of physical activity, presence of diabetic complications or other medical conditions such as heart failure, and whether there is a tendency to have hypoglycemia unawareness. Patients should aim to keep their glucose levels within their personalized range.
  

• Learn how to check glucose. Ask a physician or certified diabetes educator for a demonstration.
  
  
• Decide on a testing schedule. Some people with diabetes need to check their glucose more often than others, depending on the type of diabetes, medications and glucose levels. Ask a physician for advice on how often and at what times to test.
  

• Keep a record of results. Patients should record test results in a log book along with medication dose. Changes in food, activity, illness, stress and medication should also be noted. Some physicians may instruct patients to fax in results. Some glucose meters store test results in memory or connect to computers where results can be downloaded. Once on the computer, results can be printed for physician review or turned into simple graphs and charts.
  
  
• Look for glucose patterns. Review blood glucose records for trends in hyperglycemia or hypoglycemia. Take note if levels are too high or too low several days in a row at about the same time. Patterns can reveal conditions such as dawn phenomenon or the Somogyi effect. Glucose readings that are persistently above or below target range may mean that the diabetes management plan is not working and needs to be revised.
  
  
• Investigate what causes changes in blood glucose levels. Review the log book for fluctuations and try to connect them with their triggers. Blood glucose levels can be affected by:
  
  

  Factor	Possible effect on blood glucose levels
  Food	Increase
  Insulin or antidiabetic agent	Decrease
  Glucagon	Increase
  Non-diabetes medications	Increase, decrease or no effect
  Exercise	Decrease (generally)
  Illness	Increase (generally)
  Stress	Increase
  Alcohol	Decrease

• Decide how to get glucose levels back to target range. Patients should review their log book records with their physician and decide what changes are necessary in diet, exercise or medication.

Recent research suggests that half or more of diabetes patients have poor glycemic control and that many admit not checking their glucose often enough. Regular glucose monitoring is essential in avoiding serious consequences such as diabetic retinopathy and diabetic coma.

Scientists are trying to make glucose monitoring more convenient, comfortable and accurate. Available advances include:

• Continuous glucose monitoring (CGM). The U.S. Food and Drug Administration (FDA) has approved several of these systems for adults, and researchers are developing others. A typical CGM device measures glucose every five minutes for up to three days and is intended for occasional use, not to replace fingerstick testing. A device approved by the FDA in 2007 allows monitoring for up to seven days. One CGM device is worn like a wristwatch; others are pager-size devices with a needle-like sensor that is inserted into abdominal skin. The information is stored in the monitor’s memory and then transferred to the physician’s computer.
  
  
• Built-in glucose meters featured in some models of insulin pumps.

• Combined CGM and insulin pump. In 2006 the FDA approved an insulin pump that incorporates continuous glucose monitoring. The ultimate goal is creation of a surgically implanted artificial pancreas that requires no input from the patient.

Emerging glucose-monitoring techniques include an implantable microchip using radiofrequency identification technology to measure and send data, and software that sends glucose and blood pressure readings by cellphone to a physician’s computer.