Find Information About:

Drugs & Supplements

Get information and reviews on prescription drugs, over-the-counter medications, vitamins, and supplements. Search by name or medical condition.

Pill Identifier

Pill Identifier

Having trouble identifying your pills?

Enter the shape, color, or imprint of your prescription or OTC drug. Our pill identification tool will display pictures that you can compare to your pill.

Get Started
My Medicine

My Medicine

Save your medicine, check interactions, sign up for FDA alerts, create family profiles and more.

Get Started

WebMD Health Experts and Community

Talk to health experts and other people like you in WebMD's Communities. It's a safe forum where you can create or participate in support groups and discussions about health topics that interest you.

  • Second Opinion

    Second Opinion

    Read expert perspectives on popular health topics.

  • Community


    Connect with people like you, and get expert guidance on living a healthy life.

Got a health question? Get answers provided by leading organizations, doctors, and experts.

Get Answers

Sign up to receive WebMD's award-winning content delivered to your inbox.

Sign Up

Metformin causing higher sugar?
susanng posted:
Hi everyone!

2 weeks ago my doctor called me and told me I had a fasting lab sugar reading of 126 and my A1C was 7.0 and she said normal was 6.7. So she put me on 250mg of Metformin every morning at breakfast.
Now before this each time I checked my sugar it was always between 80 and 100.
Since then I have cut my sugar intake by 75% (I used to drink 4 pepsi's a day and now only 1 a day). I have also been watching my carb intake.
Now my sugar constantly reads over 105 up to 189(highest so far and only happened once). Could the Metformin be working the opposite on me?
glucerna responded:
This is definitely something to discuss with your doctor. Have you changed your meter or test strips? It's great you're making changes to your food choices! ~Lynn @Glucerna
susanng replied to glucerna's response:
Yes they gave me a new tester and it is just a few points differant than my old one. I occasionally check my sugar on both at the same time and usually they are only a couple points differant.
nutrijoy responded:
"...a fasting lab sugar reading of 126 and my A1C was 7.0 and she said normal was 6.7"

A FBS reading of 126 officially qualifies you as being diabetic by most standards, A1c readings of 7.0 is damaging to every organ in your body, and normal is definitely not 6.7. Anything above true normal accelerates aging of your precious cells which includes skin (most visible) and virtually every internal organ in your body. Unfortunately, this damage is rarely accompanied by physical symptoms that you can feel and thus become alarmed about. Instead, diabetes does its damage silently and insidiously if you fail to take proactive measures to control it and it IS 99.99% controllable (BTW, reducing your consumption of four carbonated beverages per day to just one does not qualify as proactive).

What are "normal" blood sugar levels? For starters, go to Jennie Ruhl's Blood Sugar 101 website to read her popular article on the subject. Be sure to read the entire page; especially the paragraphs on why blood testing labs often list abnormally elevated levels as "normal" and why some doctors dish out bad advice and opinions as to why high blood sugar levels are "good enough" for diabetics. Jennie has published several books and the 2011 edition of Blood Sugar 101 is well worth the read. She is a diabetic herself and spent many months (that morphed into years) researching peer-reviewed articles on diabetes. She provides abundant references on her website as well as her books to counter any armchair critics.

Metformin does not directly lower blood sugar in most patients. Its primary mechanism of action is three-fold. Metformin:
1. acts on the liver and causes it to produce less glucose;
2. affects the stomach and reduces the absorption of glucose from the food that you eat;
3. improves the efficiency of the insulin that the body produces (i.e., reduces insulin resistance).
It can also take several weeks for the medication to achieve proper blood titer levels in your blood stream and you may not experience detectable benefits initially (your mileage may vary).

Lifestyle changes (in your diet and exercise/activity levels) are essential to good control of blood sugar levels and it is not just fasting blood sugar levels that are important. After-meal (post prandial) levels are often even more important in determining how much damage your precious body cells/proteins are sustaining after ingesting foods that should be off limits or severely restricted. I am a strong advocate of Dr. Richard K. Bernstein 's guidelines for normalizing blood sugar levels in diabetics. His book, Dr. Bernstein's Diabetes Solution: The Complete Guide to Achieving Normal Blood Sugars , has become the virtual bible for those diabetics seeking to live a normal life free of complications. You can read various chapters of his book (2007 edition) online for free at this link . You can also download PDF copies by clicking on a chapter of your choice; then click on the PDF link that appears in the upper right corner of the respective page.

Also, welcome to the forums. Good control over this disease is not a destination but an ongoing journey. My own A1c has been 4.8 over the past two years but slipped during the holidays (4th quarter) to 4.9 when I over-indulged in desserts and some processed foods that included too-numerous sumptuous buffets in SoCal and Vegas.
glucerna replied to nutrijoy's response:
Great information nutrijoy and congratulations on managing your blood sugar so well. Susan, it sounds like your new meter is working well. Be sure to let your doctor know about the higher readings. ~Lynn @Glucerna

Helpful Tips

SGLT2 Inhibitor effect
I just read an excellent discussion of SGLT2 inhibitors on, and felt motivated to pass on a heads-up on a possible ... More
Was this Helpful?
1 of 3 found this helpful

Expert Blog

Conquering Diabetes - Michael Dansinger, MD

Dr. Michael Dansinger provides thoughtful tips for those with type 2 diabetes or pre-diabetes who want to reclaim their health...Read More

Related Drug Reviews

  • Drug Name User Reviews

Report Problems With Your Medications to the FDA

FDAYou are encouraged to report negative side effects of prescription drugs to the FDA. Visit the FDA MedWatch website or call 1-800-FDA-1088.