Test Prep

By Eileen B. Wyner, NP
Bulfinch Medical Group

Eileen W

It’s always a little nerve-wracking when you have to undergo medical tests.  Instructions  can range from very simple, to vague, to extremely detailed.  Eat, don’t eat; take some medications but not others. It makes you feel like you’re on your way to an 8th grade spelling test, convinced of a low score before even getting out of bed.  Everybody feels like that, trust me, but sometimes there are certain extra steps ot test prep if you have Diabetes.  I want to review some of the more common examples, but please note this list isn’t exhaustive.  ALWAYS check with your health care provider for specialized directions.

The timing of tests, regardless of what it is, is crucial to your Diabetes self-care.  I always suggest to patients that they get the earliest appointment of the day whenever possible. You may have to check your blood sugar more frequently if you need to fast before the test, and may need to adjust both your long and rapid acting insulin as well as oral agents such as Glyburide, Glipizide, or Glimepiride (Sulfonylureas).  In fact, you may need to hold these medications all together.

Tests requiring the use of dye also may also mean medication schedule changes.  Patients taking Metformin or Glucophage are often asked to hold these medications for up to 48 hours before and after the test (dye used in tests is cleared by the kidneys, so use of Metformin/Glucophage may cause some changes in kidney function).  Again, careful blood sugar monitoring and dietary care will be extra important during this time.

The test that causes the greatest amount of confusion for my patients, however, is the colonoscopy.  The prep for this test can start several days prior and greatly impacts diet and medication schedules.  Also, insulin doses will need to be adjusted.  Therefore, it is imperative that you review your medication dosing schedule with your care team at least one month before your test. 

I also want to stress that it may take a couple of days to get your blood sugars back on track after the test.  Any disruption in your schedule may alter your blood sugar, so careful self-monitoring is key.  Taking a little bit of time to plan ahead can make these tests a little less stressful.  And, of course, I wish you luck with all of this!