Diagnostic Tests

There may come a time when your health-care provider wants to have some tests done to help diagnose a condition or to decide the most appropriate course of action. A diagnostic test is a laboratory, or other non-invasive, invasive or imaging procedure. Non-invasive diagnostic tests include urine tests, electrocardiograms, simple X-rays, MRI and CAT scans. Invasive diagnostic tests include any non-surgical procedure that includes an insertion of a medical device or medication for the purpose of evaluating or measuring a physiological function or response.

As a pumper, there are some special considerations and actions you should take to make the procedure as stress-free as possible.

Pre-Test Preparation

As a person with diabetes and an insulin pumper, you need to know if you are required to fast for several hours before and after a procedure. You also will need to know how much time is involved for the actual procedure, as well as any special instructions to be followed after you leave the facility.

Most physician offices and diagnostic testing centers will give guidelines or pamphlets with this information. Your health-care practitioner may recommend more frequent blood-glucose tests before, during and after the procedure so you can adjust your insulin if necessary.

Tips for Insulin Pumpers to Use During Diagnostic Tests

Insulin pumps should never be exposed to strong sources of radiation or electrical interference such as X-rays, MRI or CAT scans, common in diagnostic tests. Strong magnetic fields can damage the mechanical parts of the pump.

Disconnect Before the Test Starts

It is always best to disconnect the pump before the test starts. If not previously discussed with your physician or the testing department, call the testing location a day a two before the test is scheduled and let them know about your insulin pump.

If you use a disconnecting catheter infusion set, it will be easier for you to disconnect from the pump during the procedure.

Leave the Basal Rate Running

When you disconnect, you may want to leave your normal basal rate running. If you use a “suspend” or “stop” mode, your pump will set off the periodic warning beeps, and might set off an alarm signal. You will want to explain to the staff performing your test that this is normal and there is no need for concern.

Review your pump user manual if you need a refresher on programming. Be sure to check with your physician or pump trainer regarding the best option for your situation.


Before reconnecting to your insulin pump, check for air in the infusion line, use the bolus or prime feature to clear any air and watch for at least five drops of insulin before you reattach your infusion set.

Always check with your physician about your specific glucose/insulin management.

Put the Pump in a Safe Place

The infusion site may be maintained if it is not in the area to be X-rayed, and you can reconnect when the test is completed. Put your pump in a locked storage area or have a responsible family member or friend hold it for you.

Bring an Extra Infusion Set Change

Bring an extra infusion set change and other supplies with you, just in case you need to use them.

Prevent/Manage a BG Problem

When disconnected for one to four hours, replacement of rapid-acting basal might be necessary. In some settings, an IV with insulin might be ordered if your test is two or more hours. Check with your diabetes team for any insulin replacement options. Also consider:


If you need to fast for several hours before, during or after the diagnostic procedure, your blood glucose should stay within your target range if your basal rates are established and stable. If your glucose level goes below target, glucose tablets or gel would be the best treatment.

Check with your physician about options for basal-rate reductions.

Activity Level

Any test that requires physical exertion and calorie burning has the potential to cause hypoglycemia. Exercise stress tests are physically active tests. Basal rate adjustments for exercise will most likely be needed. If you are not required to fast prior to these tests, a small meal and reduced or omitted bolus is permitted.


Procedures that cause pain or add to any pain or discomfort you already have could cause a rise in your stress hormone levels and raise your blood sugars. Neurological tests like spinal myelograms, electromyelograms (EMGs), gastro-intestinal studies and arthroscopy can be physically uncomfortable.

You might have to correct any elevations when the test is completed, but if this is something to be expected based on previous experience, it is possible to bolus the anticipated extra amount of insulin prior to disconnecting your pump.

Be sure to always test and never assume that your BGs will not go up.

Show and Tell

If the staff involved with your diagnostic procedure has not seen your pump—or any pump—this could be an opportunity to show them how it works. Ask if anyone there knows how to test your blood glucose. If not, someone there may need to learn how to do it so that they will be prepared to handle future patients on the pump.

Support Team

Discuss your diagnostic test information and your pump management options with a family member or close friend. Have an advocate with you in case you need one.

Be informed about diagnostic tests and know what to expect. This will help you with planning, maintaining, managing and troubleshooting your glucose control.

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