Glucose Problem Solving

Finding out the effects of prednisone and blood donation.

Theresa Garnero By Theresa Garnero, APRN, BC-ADM, MSN, CDE

This New Year brings questions from gentle readers about the effects of prednisone and blood donation. 

Prednisone moan

I was recently diagnosed with type 2 after a 9-day course of prednisone. My glucose went up to 370 and I went to the E.R. My doctor put me on metformin 500 mg, twice a day. I've been eating very, very carefully since this happened but my blood sugar is always in the 200 to 250 range. I have millions of questions. I understand this is manageable, but is it reversible? I was predisposed to being type 2 but a couple months ago my fasting glucose was 110. Has anybody been through this before?

This is where you will hear a collective, virtual moan from diabetes educators. Prednisone is famous for challenging the body's ability to regulate glucose. When we look at the pie chart of types of diabetes, about one percent of people get type 2 as a result of medications (notoriously prednisone). Does this mean all of the readers taking prednisone should stop it? Absolutely not. Prednisone is a steroid and it serves a purpose (helps aid in breathing for people with lung conditions, or manage the agony of severe poison oak, etc.). It's dangerous to suddenly stop prednisone. Besides, make sure to involve your healthcare provider before stopping any medications. I digress but want to be sure you are safe. Let's address the other issues raised.

You mentioned having a predisposition to getting type 2 prior to receiving cortisone therapy. A 110 fasting glucose is elevated — in the prediabetes range. It is at that stage that the research shows you have a window of time when the condition may be reversible. Once you have diabetes, regardless of the cause, it's there to stay. You might have it very tightly controlled, through a combination of sound nutrition, regular activity, and the right kind / amount of medication(s). People often labor under the false assumption that once glucose values return to normal, they no longer have diabetes. Remember, diabetes is progressive, in that half of the insulin-producing beta cells within the pancreas are destroyed by the time someone is diagnosed. The sooner you and your healthcare provider can find the right combo of food, exercise, and medication to control glucose, the better chance you'll have at protecting the remaining beta cells.

Glucose values of 250 are toxic to the beta cells, which then makes oral medications less effective. This is where temporary insulin has a place. A little insulin brings the glucose down, the pills work better, and less insulin is needed. Another common approach is to use other diabetes medications that work in different ways. Your metformin dose is half of the maximum (which your healthcare provider's did on purpose to be sure you can tolerate it, or that your liver can handle it, etc.).

You mentioned being very careful with your food choices. Congratulations! That is a challenge for the majority of people who wake up every day. Have you had education from a certified diabetes educator to be assured you are being careful about the right things? You may be making wise choices, it's just that you said you had a million questions. Without learning the skills you can apply for a lifetime from the folks who eat diabetes research for breakfast, you won't be armed with the latest tools to stay healthy. Food is a major variable, but only one of several that will impact your glucose (read more in the "Seven Wonders of Diabetes Management" article). Ask your healthcare provider about seeing a local certified diabetes educator. Best of health to you.

After someone's blood

How would giving a pint of blood 2 months before an A1C test affect the results?

From the research I could find, I do not think it would have much affect. A1Cs have a weighted value over the past three months: fifty percent of the result is related to the past month, twenty-five percent from months two and three. One pint of blood causes a reduction of iron, so it's possible to see a change. So many other variables can impact your A1C two months after donation. Readers beware: do not donate blood with the hopes to lower your A1C. That's shooting yourself in the foot. Your healthcare provider might not provide the appropriate treatment.

Thank you for your continued interest which no doubt addresses questions held by many. Keep sending those dLife emails! And Happy New Year!

Read Theresa's bio here.

Read more of Theresa Garnero's columns.

NOTE: The information is not intended to be a replacement or substitute for consultation with a qualified medical professional or for professional medical advice related to diabetes or another medical condition. Please contact your physician or medical professional with any questions and concerns about your medical condition.

Last Modified Date: January 23, 2014

All content on is created and reviewed in compliance with our editorial policy.

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