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Blood sugar monitoring: Why, when and how

Blood sugar monitoring is an essential part of diabetes care. Find out when to test your blood sugar level, how to handle poor results and more.

By Mayo Clinic staff

When you have diabetes, managing your blood sugar level is the most important thing you can do to feel your best and prevent long-term complications. Consider it an opportunity to take charge of your health.

Know your target range

Your doctor will set your target blood sugar range. For many people who have diabetes, target levels are:

  • Before meals — between 90 and 130 milligrams per deciliter (mg/dL), or 5 and 7 millimoles per liter (mmol/L), also known as your fasting blood sugar level
  • One to two hours after meals — lower than 180 mg/dL (10 mmol/L)
  • Before bedtime — between 110 and 150 mg/dL (6 and 8 mmol/L)

Remember that your target blood sugar range may differ, especially if you're pregnant or you develop diabetes complications. Your target blood sugar range may change as you get older, too. Sometimes reaching your target blood sugar range is a challenge. But the closer you get, the better you'll feel.

When to test your blood sugar

How often you need to test your blood sugar level depends on the type of diabetes you have and your individual diabetes treatment plan.

If you have type 1 diabetes, your doctor may recommend testing your blood sugar level at least three times a day — perhaps before and after certain meals, before and after exercise, and before bed. You may need to check your blood sugar level more often if you're ill or you change your daily routine.

If you take medication — with or without insulin — to manage type 2 diabetes, your doctor may recommend testing your blood sugar level once a day. If you manage type 2 diabetes with diet and exercise alone, you may need to test your blood sugar level even less often.

How to test your blood sugar

To test your blood sugar level, you'll need a blood sugar monitor. Some monitors are large with easy-to-handle test strips, while others are compact and easier to carry. Some monitors track the time and date of each test, the result and trends over time. You may even be able to download this information to your computer.

Most blood sugar monitors require you to prick your fingertip with a special needle (lancet). Some lancets allow you to adjust the prick depth to accommodate differences in skin thickness.

If you wonder which type of blood sugar monitor would be best for you, ask your doctor or diabetes educator for a recommendation. Keep in mind that your insurance provider may limit coverage to specific types of monitors.

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Jan. 4, 2008

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