Understanding Blood Glucose Monitoring

Blood glucose monitoring is the main tool people with diabetes use to see how well their management plan is working from day to day. Understanding what is being measured, and why, turns a routine finger prick into genuinely useful information.

What is being measured

Glucose comes from the food you eat and is carried in the blood to the body’s cells. A monitoring device reports its concentration. In the United States the unit is milligrams per deciliter (mg/dL); many other countries use millimoles per liter (mmol/L).

Why monitoring matters

Regular monitoring helps you:

• see how meals, exercise, stress and illness change your glucose;
• know whether your medicines are working;
• detect low or high blood sugar before it becomes dangerous;
• make informed decisions with your healthcare team;
• track progress toward your treatment goals.

The CDC describes regular monitoring as the most important thing you can do to manage type 1 or type 2 diabetes.

The two main methods

Blood glucose meter

A meter measures glucose in a small drop of blood, usually from the fingertip. You place the drop on a disposable test strip inserted in the meter, and the result appears within seconds. A meter shows your level at that single moment.

Continuous glucose monitor (CGM)

A CGM uses a small sensor placed under the skin, usually on the arm or abdomen. It measures glucose in the fluid between cells every few minutes, day and night, and sends readings to a receiver or smartphone. People who use a CGM may still need a meter to confirm some readings.

Who should monitor

Your doctor decides whether home monitoring is right for you. It is generally essential for people who:

• take insulin;
• are pregnant;
• have difficulty reaching their glucose targets;
• have low blood sugar, particularly without the usual warning signs.

Some people with type 2 diabetes who do not use insulin are advised to test less often or not routinely. Follow your own team’s guidance.

Typical times to check

• When you first wake up, before eating or drinking
• Before a meal
• Two hours after the start of a meal
• At bedtime

People who take insulin, or who often have low blood sugar, may be asked to check more often, for example before and after physical activity.

Typical targets

The CDC lists these common targets for many adults with diabetes:

• Before a meal: 80 to 130 mg/dL
• Two hours after the start of a meal: less than 180 mg/dL

Targets are individual. Age, pregnancy, other health conditions and the risk of low blood sugar can all change them. Use the numbers your team gives you.

Monitoring versus the A1C test

A meter or CGM gives real-time information. The A1C test, carried out in a clinic or laboratory, shows your average glucose over the past two to three months. The two complement each other: daily readings explain how you arrived at your A1C.

Making results useful

• Record the date, time and result, or use the meter’s memory.
• Note meals, activity, illness or missed medicines that may explain a reading.
• Look for patterns over several days.
• Take your records to every appointment.

Never change your medicine dose on the basis of home readings unless your team has shown you how.

What you need to get started

A meter, matching test strips, a lancing device and lancets, and a sharps container. Our Blood Glucose Monitoring Kit includes a meter, lancing device, starter strips and lancets.

The bottom line

Monitoring turns blood sugar from a guess into a number you can act on with your healthcare team. See meters and supplies in our diabetes care range.

Sources

1. Centers for Disease Control and Prevention. Monitoring Your Blood Sugar.
2. American Diabetes Association. Check Your Blood Glucose.
3. National Institute of Diabetes and Digestive and Kidney Diseases. Managing Diabetes.
4. MedlinePlus. Blood Glucose.