Should Diabetes Medication Be Taken During Fasting and Post-Meal Glucose Testing?
Patient's Query
Earlier my physician clearly told me: for fasting and post-breakfast sugar tests, I should take my tablets as usual and not skip them. I have been doing that.
Now I’m bringing my mother for the same tests. She is on insulin (and sometimes tablets also). I’m confused: on the test day, should she take her insulin and tablets as per routine, or should we skip them because she is fasting for the blood sample?
What is the correct way so that the report is meaningful and we don’t cause low sugar?
Endocrinologist Answers
In most cases, for follow-up diabetes testing, you should continue your medicines exactly as you take them on a normal day.
Why?
These tests are usually done to check how well your diabetes is controlled on your current treatment.
If you skip tablets or insulin, the report becomes an “artificially high” number and may lead to wrong dose changes (sometimes even causing low glucose later).
A simple “correct test day” plan
If your doctor asked for fasting and post-breakfast glucose (PPBS):
- Go fasting (as the lab instructed).
- Give the fasting sample.
- Take your usual breakfast and your usual diabetes medicines (tablets and/or insulin) the same way you do daily.
- Give the post-meal sample at 1-2 hours after starting the meal (many labs use 2 hours; the key is consistency).
What about insulin specifically?
- Never “experiment” by skipping insulin on your own.
- Many people need insulin because their body’s insulin is not enough or not working well. If you skip insulin, glucose can rise significantly.
- If you are fasting longer than usual, or you have a history of low glucose, your doctor may give a custom plan (dose adjustment). Do not guess.
What about HbA1c?
- HbA1c does not require fasting, and it reflects average Glucose over ~3 months.
- You usually continue your routine medicines unless your doctor tells you otherwise.
When might a doctor tell you to stop or change medicines?
Only in specific situations, for example:
- You are being tested for new diagnosis of diabetes or special evaluation.
- You are having frequent hypoglycemia, kidney issues, or you are acutely unwell.
- Your doctor wants a supervised “off-medication” assessment (uncommon and individualized).
One-line takeaway
For routine follow-up fasting and post-meal glucose tests, test your glucose on a “normal day routine”, not on a “skipped medicine day”.
Disclaimer: This is general education. Always follow the plan given by your treating doctor, especially if you are on insulin or have a history of low glucose.
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Disclaimer: The information provided in this Q&A is for educational purposes only and should not be considered as medical advice. Always consult with a qualified healthcare professional for personalized medical guidance and treatment recommendations.