Generally, healthcare professionals recommend checking blood sugar before meals and at bedtime. However, this can vary depending on a person’s diabetes management plan.

When a person has type 2 diabetes, their body cannot regulate the volume of sugar, or glucose, in their blood. Regular monitoring of blood sugar levels can be a key tool for managing the condition.

Read on to learn about the benefits, how to check blood sugar levels, the best time to check, and more.

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A person with type 2 diabetes may have too much sugar — also called glucose — in their blood. Glucose is the primary source of energy for all cells.

Type 2 diabetes causes problems with the production or use of insulin, a hormone that breaks down blood glucose. This means the glucose stays in the bloodstream.

If a person has too much glucose in their blood, they can experience complications such as:

  • bladder problems
  • eye disease
  • foot problems
  • gum disease
  • heart disease
  • high blood pressure
  • kidney disease
  • nerve problems
  • skin conditions

According to the Centers for Disease Control and Prevention (CDC), people with type 2 diabetes should regularly monitor their blood glucose. They can check their levels before or after:

  • eating
  • taking medication
  • participating in physical activity

A person and their doctor can use this information to create an effective treatment plan. With a customized plan, a person can reduce their risk of serious health complications.

Not everyone may check their blood sugar at the same times. A person with type 2 diabetes should talk with a healthcare professional about how often to check their blood glucose levels.

For people who can eat a typical diet, doctors generally recommend checking blood glucose levels before meals and at bedtime.

For people who are receiving enteral nutrition — which goes directly into the stomach or small intestine — and those who are staying in a hospital and cannot eat for medical reasons, doctors recommend checking every 4–6 hours.

The HbA1c test, which people may also call hemoglobin A1c or A1C, measures a person’s average blood sugar levels over the previous 3 months. It can help a person and their doctor detect trends in their blood sugar levels.

People most commonly check their blood glucose levels using a blood glucose meter. To use a blood glucose meter, the American Diabetes Association (ADA) recommends that a person do the following:

  1. Read the instructions for their specific type of meter.
  2. Wash their hands.
  3. Insert a test strip into the meter.
  4. Pierce the side of their fingertip with a lancet — a small plastic device holding a needle — to get a drop of blood.
  5. Hold the edge of the test strip to the drop of blood.
  6. Read the blood glucose level on the meter’s display.

Some people check their blood sugar with continuous glucose monitoring. In this case, a monitoring device requires a person to have a tiny sensor inserted under their skin. Every few minutes, the sensor takes a reading of the amount of glucose in the interstitial fluid, which is the fluid between a person’s cells.

This shows the changes in their glucose levels over time.

However, measuring glucose in this way causes a delay in the reading, so a person should still do occasional finger-prick blood tests to check that the device is accurate.

Learn more about how to check blood glucose at home.

To accurately measure their blood sugar, a person should record all their blood glucose test readings.

A person may want to record their measurements in:

  • a paper diary or notebook
  • a cellphone calendar
  • some types of glucose meters
  • a diabetes cellphone app

They can then review the results with their healthcare team to see whether any changes to their diabetes care plan are necessary.

A person should discuss their individual blood glucose target ranges with a healthcare professional.

There is no one-size-fits-all target range. A variety of factors can affect a person’s target range, including:

  • how long they have had diabetes
  • their age
  • any other health conditions they have
  • whether they have cardiovascular disease or diabetes complications
  • how aware they are of hypoglycemia, or low blood sugar
  • other factors unique to the individual

The ADA says that for most adults, excluding pregnant people, A1C should be lower than 7%. People can also aim for an estimated average glucose (eAG) of less than 154 mg/dL.

To understand the effect that eating has on blood glucose levels, a person should check their preprandial (before a meal) glucose level. The reading should be between 80 and 130 mg/dL.

They should check their postprandial (after a meal) glucose level 1–2 hours after eating. This reading should be lower than 180 mg/dL 2 hours after eating.

A person may need medical help if they experience hypoglycemia, which is a reading below 70 mg/dL. They can try to raise their blood sugar by:

  • taking four glucose tablets
  • drinking 4 ounces of fruit juice or regular soda (not diet soda)
  • eating four pieces of hard candy

Healthcare professionals often recommend the 15–15 rule for treating low blood sugar. This involves eating 15 grams of carbs, waiting 15 minutes, and repeating the blood sugar test. If a person’s blood sugar is still lower than 70 mg/dL, they can repeat the 15 grams of carbs.

However, if this does not help, they should seek medical attention.

If a person witnesses someone with diabetes experiencing severe hypoglycemia and becoming unconscious, they should:

  • turn the person onto their side
  • give them a glucagon injection, if possible
  • call 911 if glucagon is not available or if the glucagon has not worked within 10 minutes

Having regular hypers, or states of hyperglycemia — meaning high blood sugar — can lead to the diabetes complications mentioned above. Hyperglycemia is a fasting blood sugar level higher than 125 mg/dL and a postprandial blood sugar level higher than 180 mg/dL.

In this case, a person should contact a healthcare professional to review their diabetes care plan and get their blood sugar levels back down to within their target range.

Type 2 diabetes causes problems with the production or use of insulin, a hormone the body needs to help blood sugar enter the cells to provide energy. Checking blood sugar levels regularly is a key way for a person with type 2 diabetes to manage their condition.

A person should consult a healthcare professional to find out exactly when they should check their levels. Typically, people should check before meals and before bed.