Fact Sheet

Self-Monitoring of Blood Glucose

  • Editors
  • Amparo Gonzalez, RN, BSN, CDE
    James L. Rosenzweig, MD
    Guillermo Umpierrez, MD

What is diabetes?

Diabetes is a disease in which levels of glucose (sugar) in the bloodstream are higher than normal.  Your body makes glucose from the foods you eat.  Insulin is a hormone produced by the pancreas (an organ located in your abdomen).  It takes glucose from the bloodstream and carries it into your cells where it is used for energy.  With diabetes, glucose does not enter the cells and builds up in the blood.

There are three main types of diabetes:

Did you know?

Checking your blood glucose levels regularly can help you take care of yourself and your diabetes.

Why is it important to monitor your blood glucose levels?

Over time, uncontrolled diabetes may cause serious complications including heart disease, stroke, kidney failure, blindness, and nerve damage.  Keeping blood glucose levels close to normal is the key to preventing these health problems..

You should monitor your glucose levels regularly and get familiar with your pattern of glucose readings at different times of the day.  Regular self-monitoring provides valuable information that your health care team can use to make decisions about medication and insulin, and improve control of your diabetes.

Checking your blood glucose also helps prevent immediate problems that can result from glucose levels that are too high (hyperglycemia) or too low (hypoglycemia).  Both problems can be serious if not treated right away.

How do you check glucose levels?

You can check your blood glucose using a small battery-operated meter.  You put a drop of blood, usually from a finger or forearm prick, on a chemically-coated strip. The meter will read your glucose level from the strip.  In the U.S., meters display the glucose level in milligrams per deciliter (mg/dL).


Different types of meters are available to measure your blood glucose level.  When choosing a meter, here are some features to consider:

Talking meters are also available for people who have impaired visionvisually impaired.

How often people with diabetes need to check their blood glucose varies from person to person.

So does their recommended target level. Be sure to talk with your health care provider about what is best for you.

Some people with type 1 diabetes use a continuous glucose monitoring (CGM) system.  The system measures glucose levels in the fluid between body cells every few minutes throughout the day and night. Your health care provider can explain how CGM works and whether it might be right for you.

General Guidelines for Monitoring Blood Glucose

Type of diabetes

  • Type 1
  • Type 2 with insulin
  • Type 2 with oral medicines
  • Diabetes of pregnancy

Number of checks

  • Type 1: 3 or more per day
  • Type 2 with insulin: 2 or more per day
  • Type 2 with oral medicines: 1 or 2 per day. With good blood glucose control, 3 days per week. With poor control, daily
  • Diabetes of pregnancy: At least 4 to 6 per day


  • Type 1: Before meals; 2 hours after meals
  • Type 2 with insulin: Before meals; 2 hours after meals
  • Type 2 with oral medicines: Before meals; 2 hours after meals
  • Diabetes of pregnancy: Before meals; 1 or 2 hours after meals

Recommended target levels

  • For all Types: Before a meal: 90-130 mg/dL Two hours after a meal: below 180 mg/dL

When should you call your doctor?

How can you use your blood glucose readings?

You can take an active role in your medical care by using your readings to keep your blood glucose levels under control.  Keep a written record of your blood glucose readings and highlight any that are higher or lower than your target.  When you have an unusual reading, make notes on any factors that might have affected your glucose level. These could include what you ate, exercise patterns, if you’re sick, if you missed taking medication or insulin, and positive or negative emotions.  Then share this information with your health care providers so they can evaluate your diabetes care program and make changes if necessary.

Questions to ask your doctor