Blood sugar targets and home glucose checks: what the numbers mean

People often ask what a good blood sugar number is. The answer depends on who you are, how long you have had diabetes, your medicines and your other health conditions. This article gives the general figures used by the NIDDK for many adults, and explains why your own targets may differ. Your care team sets your goals.

Why targets matter

The NIDDK says the aim of managing blood glucose is to lower the risk of complications. High blood glucose over time can harm the eyes, kidneys, nerves and heart. But very tight targets are not right for everyone. The NIDDK says keeping A1C below 7% may reduce the risk of complications for some people, but may not be safe for others, such as those at risk of low blood glucose.

General targets for many adults

The NIDDK's managing diabetes page gives these general targets and stresses they should be confirmed with your team:

• A1C: below 7%
• Before meals: 80 to 130 mg/dL
• About 2 hours after a meal starts: below 180 mg/dL
• Time in range with a continuous glucose monitor: 70 to 180 mg/dL, at least 70% of the time
• Low blood glucose: below 70 mg/dL
• High blood glucose: above 180 mg/dL

The NHS describes low blood sugar as usually below 4 mmol/L. If you use mmol/L, ask your care team to convert your targets.

When targets may be different

The NIDDK says targets may differ if you are over 65 with long-term diabetes, have heart disease or often have low blood glucose. On its A1C page, the NIDDK says a goal of 7% to 8%, or sometimes higher, may suit people with limited life expectancy, long-standing diabetes that is hard to control, severe or unnoticed hypoglycemia or advanced complications. It also says blood pressure goals may differ, with the NIDDK's managing diabetes page giving below 130/80 mm Hg for some people.

Checking at home

The NIDDK says that people who use insulin or other diabetes medicines may be advised to check blood glucose at home and keep a record of results, meals and activity. It adds that people with type 1 diabetes may also be asked to check urine for ketones. For type 1 diabetes, the NHS says to check glucose at least 4 times a day (5 for children), including before meals and at bedtime, and more often around exercise, alcohol or illness. How often you check is a decision for your care team, since it depends on your type of diabetes and medicines.

Meters and CGM

A standard meter gives a reading at one moment. A continuous glucose monitor gives readings through the day and shows trends, according to the NIDDK. Neither is used to diagnose diabetes. The NIDDK says a home glucose meter cannot diagnose diabetes.

The A1C test

The A1C test shows average blood glucose over about 3 months. The NIDDK says people with diabetes should have it at least twice a year, and more often if goals are not being met. The NHS says every 3 to 6 months is typical for people with type 2 diabetes. Bring your glucose log and A1C results to your appointments.

Spotting lows and highs

Learn the signs of both. The NIDDK lists shakiness, hunger, dizziness and confusion for lows, and the NHS lists thirst and frequent urination among signs of very high glucose. Tell your care team if you often see readings outside your range.

When to see a doctor

Speak to your care team if your readings are often outside your targets, if you have frequent lows, or if you are unsure how to use your meter or record your results. Ask what your own targets should be and how often to check.

Seek emergency help for fainting, a seizure, confusion with drowsiness, fruity-smelling breath or trouble breathing. In an emergency, call your local emergency number (112 in India, 911 in the United States).

This article is for education only and does not replace advice from your own doctor.