Blood Glucose Self-Monitoring

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

Additional Resources
Mayo Clinic

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 United States, 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:

  • Meter size
  • Amount of blood needed for the sample
  • How long it takes to display the reading
  • Ease in reading the display
  • Ability to save the results in the meter’s memory and download to a computer
  • Cost of the meter and strips
  • Whether sites other than the finger can be used to get a blood sample

Talking meters are also available for people who have impaired vision visually 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
  • Gestational diabetes

Number of checks

  • Type 1: three or more per day
  • Type 2 with insulin: two or more per day
  • Type 2 with oral medicines: one or two per day. With good blood glucose control, three days per week. With poor control, daily
  • Gestational diabetes: At least four to six per day


  • Type 1: Before meals: two hours after meals
  • Type 2 with insulin: Before meals; two hours after meals
  • Type 2 with oral medicines: Before meals; two hours after meals
  • Gestational diabetes: Before meals; one or two 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?

  • If your blood glucose is less than 60 mg/dL once, or is often less than 70 mg/dL (or the target set for you by your health care provider)
  • If your blood glucose is higher than 180 mg/dL for more than one week, or if you have two readings in a row above 300 mg/dL

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

  • What’s the best type of blood glucose meter for me?
  • How can I learn to use my blood glucose meter?
  • How often should I check my blood glucose level?
  • When should I call your office about my blood glucose levels?
  • How often will I need check-ups?
  • Should I see a diabetes educator?
  • Should I see an endocrinologist for my care?