Information, Symptoms, Treatments and Resources

Interpreting Blood Glucose Levels

Blood Glucose Monitoring Checks

Blood glucose monitoring is the main tool you have to check your diabetes control. This check tells you your blood glucose level at any one time. Keeping a log of your results is vital.

Here is a table that lists blood glucose ranges for adults with diabetes:


Glycemic control 




Preprandial plasma glucose (before a meal)

70–130 mg/dl (5.0–7.2 mmol/l)

Postprandial plasma glucose (after a meal)

<180 mg/dl (<10.0 mmol/l)

Blood pressure

<130/80 mmHg




<100 mg/dl (<2.6 mmol/l)


<150 mg/dl (<1.7 mmol/l)


>40 mg/dl (>1.1 mmol/l)



Keeping a log of your results is vital.

Who Should Check?

Experts feel that anyone with diabetes can benefit from checking their blood glucose. The American Diabetes Association recommends blood glucose checks if you have diabetes and are:

  • taking insulin or diabetes pills 
  • on intensive insulin therapy 
  • pregnant
  • having a hard time controlling your blood glucose levels
  • having severe low blood glucose levels or ketones from high blood glucose levels
  • having low blood glucose levels without the usual warning signs

Urine Checks

Urine checks for glucose are not as accurate as blood glucose checks. Urine testing for glucose should not be done unless blood testing is impossible.

A urine check for ketones is another matter. Checks for ketones need to be made when you feel that your diabetes is out of control or in the case of illness.  When your body is burning fat instead of glucose for fuel, the amount of ketones noticeable in your urine will be great. The reason for this is that there is too little insulin at work in your body. If you are unsure of how to check for ketones in your urine, consult your doctor

How Blood Checks Work


You ***** your finger with a special needle, called a lancet, to get a drop of blood. With some meters, you can also use your forearm, thigh or fleshy part of your hand. There are spring-loaded lancing devices that make sticking yourself less painful. Before using the lancing device, wash your hands or site you chose with soap and water. If you use your fingertip, stick the side of your fingertip by your fingernail to avoid having sore spots on the frequently used part of your finger.

Checking With a Blood Glucose Meter

Blood glucose meters "read" your blood glucose. In all types of meters, your blood glucose level shows up as a number on a screen. Be sure your doctor or nurse educator shows you the correct way to use your meter. With the advances in blood glucose meters, use of a meter is better than visual checking.

How to Pick a Meter

  • What meter does your doctor or diabetes educator suggest? They may have meters that they use often and know best. 

  • What will it cost? Some insurance companies will only pay for a certain meter. Call your insurance company before you purchase a meter and ask how to get a meter and supplies. If your insurance company does not pay for blood glucose checking supplies, rebates are often available toward the purchase of your meter. You still have to consider the cost of the matching strips and lancets. Shop around.

  • How easy is the meter to use? Methods vary. Some have fewer steps than others. 

  • How simple is the meter to maintain? Is it easy to clean? How is the meter calibrated (set correctly for the batch of strips you are using)?


Are meters accurate?

Experts testing meters in the lab setting found them accurate and precise. However, meter mistakes most often come from the person doing the blood checks. For good results you need to do each step correctly. Here are other things that can cause your meter to give a poor reading:

  • a dirty meter 
  • a meter or strip that's not at room temperature
  • an outdated test strip 
  • a meter not calibrated (set up for) the current box of test strips 
  • a blood drop that is too small

Ask your health care team to check your skills at least once a year.

Logging Your Results

When you finish the blood glucose check, write down your results and use them to see how food, activity and stress affect your blood glucose. Take a close look at your blood glucose record to see if your level is too high or too low several days in a row at about the same time. If the same thing keeps happening, it might be time to change your plan. Work with your doctor or diabetes educator to learn what your results mean for you. This takes time. Ask your doctor or nurse if you should report results out of a certain range at once by phone.

Keep in mind that blood glucose results often trigger strong feelings. Blood glucose numbers can leave you upset, confused, frustrated, angry, or down. It's easy to use the numbers to judge yourself. Remind yourself that your blood glucose level is a way to track how well your diabetes care plan is working. It is not a judgment of you as a person. The results may show you need a change in your diabetes plan.



 Checking for Ketones

You may need to check your urine for ketones once in a while. Ketones in the urine is a sign that your body is using fat for energy instead of using glucose because not enough insulin is available to use glucose for energy. Ketones in the urine is more common in type 1 diabetes.

Urine tests are simple, but to get good results, you have to follow directions carefully. Check to be sure that the strip is not outdated. Read the insert that comes with your strips. Go over the correct way to check with your doctor or nurse.

Here's how most urine tests go:

  • Get a sample of your urine in a clean container.
  • Place the strip in the sample (you can also pass the strip through the urine stream).
  • Gently shake excess urine off the strip. 
  • Wait for the strip pad to change color. The directions will tell you how long to wait.
  • Compare the strip pad to the color chart on the strip bottle. This gives you a range of the amount of ketones in your urine.
  • Record your results.

What do your results mean? Small or trace amounts of ketones may mean that ketone buildup is starting. You should test again in a few hours. Moderate or large amounts are a danger sign. They upset the chemical balance of your blood and can poison the body. Never exercise when your urine checks show moderate or large amounts of ketones and your blood glucoser is high. These are signs that your diabetes is out of control. Talk to your doctor at once if your urine results show moderate or large amounts of ketones.

Keeping track of your results and related events is important. Your log gives you the data you and your doctor and diabetes educator need to adjust your diabetes care plan.

When to Test

Ask your doctor or nurse when to check for ketones. You may be advised to check for ketones when:

  • your blood glucose is more than 300 mg/dl 
  • you feel nauseated, are vomiting, or have abdominal pain 
  • you are sick (for example, with a cold or flu) 
  • you feel tired all the time 
  • you are thirsty or have a very dry mouth 
  • your skin is flushed 
  • you have a hard time breathing your breath smells "fruity" 
  • you feel confused or "in a fog"


These can be signs of high ketone levels that need your doctor's help.


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