blood sugar testing by pricking finger

This fascinating compound was discovered nearly a century ago. Scientists realized that it could lower blood sugar in an animal model (rabbits) as early as 1929 but it wasn’t until the late 1950s that a French researcher came up with the name Glucophage (roughly translated as glucose eater). The FDA gave Glucophage (metformin) the green light for the treatment of type 2 diabetes in 1994, 36 years after it had been approved for this use in Britain.

Uses of Generic Metformin:

Glucophage lost its patent protection in the U.S. in 2002 and now most prescriptions are filled with generic metformin. This drug is recognized as a first line treatment to control blood sugar by improving the cells’ response to insulin and reducing the amount of sugar that the liver makes. Unlike some other oral diabetes drugs, it doesn’t lead to weight gain and may even help people get their weight under control.

Starting early in 2000, sales of metformin were challenged by a new class of diabetes drugs. First Avandia and then Actos challenged metformin for leadership in diabetes treatment. Then Avandia lost its luster because it was linked to heart attacks and strokes. Sales are now miniscule because of tight FDA regulations.

Actos is coming under increasing scrutiny as well. The drug has been banned in France and Germany because of a link to bladder cancer. The FDA has also required Actos to carry its strictest black box warning about an increased risk of congestive heart failure brought on by the drug.

Metformin As First-Line Treatment for Type 2 Diabetes:

This all means that metformin has regained its reputation as the best bang for the buck when it comes to type 2 diabetes management. The American College of Physicians has recommended metformin as the first line of treatment when lifestyle changes (diet, exercise and weight loss) have not led to adequate blood glucose control. That may be why nearly 50 million metformin prescriptions were dispensed in 2011. Despite a large number of new medications for type 2 diabetes, metformin still seems to offer the best value.

Despite all the warm, fuzzy feelings about metformin for type 2 diabetes, there are some caveats. This drug does cause a number of side effects, especially when it comes to the gastrointestinal tract. They can be especially bothersome during the first few weeks of treatment. After several weeks, however, the digestive symptoms often fade away. If they recur, notify your doctor immediately as they could be symptoms of lactic acidosis (see below). Here is a list of adverse reactions to watch out for:

METFORMIN SIDE EFFECTS

  • Heartburn
  • Stomach ache
  • Diarrhea
  • Gas
  • Headache
  • Nausea
  • Loss of appetite
  • Weakness
  • Rash
  • Lactic acidosis (symptoms may include irregular heart rate, nausea, stomach pain, lethargy, anxiety, low blood pressure and rapid heart rate) Notify your physician immediately if you notice any of these symptoms!

These side effects may seem daunting, but most people tolerate metformin quite well. The drug can be dangerous for people with kidney disease, however. They should not take the drug, and everyone on metformin should have their kidney function monitored regularly (at least once a year). People with congestive heart failure should not take metformin either.

Metformin Against Cancer:

There is an unexpected bonus to metformin therapy. There is growing evidence that this drug has an anti-cancer effect that may prevent cancers from both developing and spreading. In particular, there are data suggesting that metformin may lower the risk of developing breast cancer, liver cancer, pancreatic cancer and colorectal cancer in people with diabetes and that the overall risk of developing cancer in such patients is substantially lower. More about this below.

A final word of caution, though. There are some nutritional consequences of metformin therapy. Here are some stories from readers. Please add your own comments about metformin treatment below theirs.


Q. I have read that metformin can cause a deficiency of Vitamin B12. I have not been able to find again the source of this information and would like your input.

Abigail

A. This is from the prescribing information at DailyMed, identical to what is published in the PDR:

“Vitamin B12 Levels: In controlled clinical trials of metformin of 29 weeks duration, a decrease to subnormal levels of previously normal serum Vitamin B12 levels, without clinical manifestations, was observed in approximately 7% of patients. Such decrease, possibly due to interference with B12 absorption from the B12-intrinsic factor complex, is, however, very rarely associated with anemia and appears to be rapidly reversible with discontinuation of metformin or Vitamin B12 supplementation. Measurement of hematologic parameters on an annual basis is advised in patients on metformin and any apparent abnormalities should be appropriately investigated and managed (see PRECAUTIONS: Laboratory Tests).
Certain individuals (those with inadequate Vitamin B12 or calcium intake or absorption) appear to be predisposed to developing subnormal Vitamin B12 levels. In these patients, routine serum Vitamin B12 measurements at two- to three-year intervals may be useful.”


Q. My husband took metformin for years with no known side effects. Then his kidney functions started to deteriorate so he was seen by a specialist who immediately took him off metformin. He said that drug was very hard on kidneys and anyone who had any variations in kidney functions should not be taking it.

A. As mentioned above, kidney function must be monitored regularly to prevent just such a complication.


Q. I am suffering from such severe diarrhea I am sometimes afraid to leave the house. I also have bad gas and bouts of abdominal pain. I suspect the metformin I take for diabetes, but my doctor says my symptoms are not from my medicine.
The Prevacid I take for my heartburn isn’t helping enough to justify the expense. I am also experiencing pain and tingling in my toes.

A. Metformin (Glucophage) can cause diarrhea, nausea, heartburn, flatulence and stomachache. Acid-suppressing drugs like lansoprazole (Prevacid), omeprazole (Prilosec) or esomeprazole (Nexium) won’t solve the problem completely and may interfere with absorption of vitamin B12.
Metformin is also linked to reduced levels of vitamin B12. Because this vitamin is crucial for nerve function, deficiency can contribute to numbness, tingling or pain of the toes, feet or fingers, trouble walking, memory problems, depression, confusion and burning tongue.

The Miracle of Metformin

Before you give up on metformin because of side effects and scary stories, we want to tell you about some surprising benefits of this drug. There is growing evidence that metformin may have impressive anti-cancer activity. Not only does the drug seem to reduce the risk of developing a number of common cancers but it might reduce the spread of cancer once it is diagnosed.

Researchers are beginning to tease out one of the proposed mechanisms for the anti-tumor action of metformin, especially in prostate cancer. A study in the journal Prostate Cancer and Prostatic Diseases (Jul. 28, 2015) reported that effective treatment for aggressive or advanced disease is challenging. The researchers note:

“One potential target is the cancer stem cell (CSC). CSCs have been described in several solid tumors, including prostate cancer, and contribute to therapeutic resistance and tumor recurrence. Metformin, a common oral biguanide used to treat type 2 diabetes, has been demonstrated to have anti-neoplastic effects. Specifically, metformin targets CSCs in breast cancer, pancreatic cancer, glioblastoma and colon cancer.”

By exploiting a metabolic weakness in cancer stem cells, metformin theoretically makes these problem cells more vulnerable to conventional cancer therapies and could reduce the likelihood of cancer resistance and recurrence. One study found that women with endometrial cancer were less likely to have a recurrence if they were taking metformin (International Journal of Gynecological Cancer, online Nov. 19, 2015).

The Bottom Line

Metformin is an old diabetes drug that is being rediscovered for its potential role against cancer. Only time will tell whether it will live up to initial expectations. In the meantime, metformin remains one of the least expensive prescription drugs in the pharmacy. As long as people are vigilant about side effects and complications it could become one of the most intriguing drugs on pharmacy shelves. Here is a link to our article “Is Metformin a Modern Miracle Medicine?

If you would like to learn more about diabetes care in general and metformin in particular you will find a wealth of information in our diabetes chapter in the book, Best Choices from The People’s Pharmacy. This special edition is 524 pages and is not available in bookstores. During our Black Friday 20% sale (good from Friday, November 27 through November 30) you will get 20% off everything in The People’s Pharmacy store, including Best Choices. A FREE tube of our Pomegranate Natural Lip Balm is included with each shipped order. The special Black Friday discount coupon is: BLKFRI20. Use it when you check out!

Join Over 120,000 Subscribers at The People's Pharmacy

Each week we send two free email newsletters with breaking health news, prescription drug information, home remedies and a preview of our award-winning radio show. Join our mailing list and get the information you need to make confident choices about your health.

  1. Kelly
    Reply

    I have been on Metformin 1000 mg daily for a year or so now. I have terrible restless legs and feet pain. I have been on several medications with little to no relief of my pain. The medications that I take for restless legs have caused me terrible side effects. Could Metformin be the cause. I am vitamin B12 deficient and do take 1000 mg daily.

  2. cheryl
    illinois
    Reply

    I have been on metformin for about six years. For most of those years I had all the classic stomach problems that goes along with this drug- especially diarrhea on a regular basis and stomach cramps. One day I saw a comment someone posted on taking probiotics for this problem. I went to the local Wal-Mart and bought the cheapest brand there and started taking one per day. I have not hand any stomach problems or diarrhea since. I hope this info helps someone else.

  3. KWF
    Ozark, MO
    Reply

    I have several similar experiences, especially gas and bloating. I also believe generics by different manufactures can be very different results, including signifant size tablets and density. I have read all comments regarding metformin and identify with several side effects. I just received CT test results and am concerned with results. Will call Dr. Tomorrow for full discussion of 2.6 cm cortical cyst upper pole right right kidney. parapelvic cyst versus dilated collecting system left kidney unchanged. I don’t know what unchanged means. CT shows other issues without explanation.

  4. Austin
    Australia
    Reply

    In October of 2014, I decided that it was time for me to take charge of my own health. I had tried several meds for Diabetes type 2 without success, and no way was I going to be a ‘lab rat’ for Big Pharma any more, so off I went on a journey of weight loss and dietary restriction.

    By June of 2015, I had lost 20 kilograms, had dumped off junk food for the most part, and had gotten rid of high blood pressure, and cholesterol problems from my life. Some 7 months later, I have lost another 15 kilos, as weight loss seems easier now, having developed some good habits and also added several supplements to my diet in that time (I use Manuka honey, bee pollen – the natural grains, not the capsules, and take Metamuscil as a dietary digestion fix) and have exercised by walking daily, or riding my 3 wheeler bike morning and evening.

    However, a recent visit to the hospital to treat an injury also showed my A1C levels had spiked to over 21!!! So the doctors put me on Metformin AP 6 weeks ago, but so far I have not noticed any side effects (500 mgs per day) and my DT2 symptoms have definitely disappeared.

    So far, so good, but I’ll come back and let the board here know if any side effects occur. I’m in my mid fifties and have much better health than I did 18 months ago, and that’s why I finally realised that my journey was not just about weight loss, as that is only the first step along the way. It’s really all about lifestyle change, and that is what is giving me much better health.

    However, the Metformin is still an unknown factor, so I’ll be keeping a steady eye on its performance… no more la brats at my place… :)

  5. Loretta
    Illinois
    Reply

    I think I need a second opinion. I was given these meds based on a test two weeks after lab-work.
    No problems with blood sugar prior too. I have had chills, stomach problems and at times very tired. My fasting blood sugar has never been over 106. I think my doctor made a mistake. Blood sugar were 88, 91, 90, 83. I had an A1C of 6.5.

  6. Char
    Reply

    I started with metformin several years ago. I first noticed I wasn’t hungry which was good but then found myself having to force myself to eat. Then the stomach problems started. I could hardly make it to the bathroom in time! I was constantly have cramps, diarrhea, and lose of appetite. All I could stomach was rice! I talked with my doctor and he said to cut back the dose for a week then restart. I finally had to start seeing a new doctor because my former doctor told that the metformin was not causing my problems. It’s funny because I didn’t have problems before metformin and they stopped as soon as I quick taking them.

    • Stephan S
      Wheeling WV
      Reply

      Took metformin fora couple of years before any problems developed. Then bathroom 4 to 5 times a day, lost 40 pounds. Found out that I needed digestive enzymes, lipase, protease and amylase. Was like flipping a switch. Digestive issues went away almost with the first dose. Have gained weight, not too much. Bathroom once a day or less sometimes.

  7. Frank Lucas
    US
    Reply

    I started metformin in November of ’97. I had some stomach uneasiness for a few week, which went away. The pill I was taking was a big, white chalky pill two twice a day. I was put on Janumet about four years ago (circa 2011), with no noticeable side effect. I was receiving Janumet through Patient Assistance. The manufacturer stopped the assistance in June of 2015, so I was prescribed metformin, again. These pills were similar to an aspirin but slightly larger. Over the next five months, I developed every side effect of metformin. I visited a GI specialist who told me that the results of five tests he had the hospital lab perform came back negative. He had reviewed my hospital record and suggested that I stop metformin. A week later, the nightmare was over. Was it metformin or a change in manufacturer?

  8. Angie
    St. Louis, MO
    Reply

    I have been on metformin since I was diagnosed several years ago. About a year ago, my neuropathy became debilitating. Just going to the store for maybe an hour kept me off my feet for 2 days. I have had my B-12 levels checked periodically and they were normal. After reading info on this site about metformin and B-12 deficiency, I talked to my podiatrist. He suggested a B-Complex. I have been on it for about 2 weeks and the difference is amazing. My feet hardly hurt at all, I can bend my toes more that I have been able to in a long time and I think I am getting a little feeling back in areas that are numb. I have suffered terribly for a year because doctors prescribe medicines without really knowing the side effects. Metformin and B-complex need to be prescribed and taken together. Doctors NEED to know this! Now I’m going to talk to my doctor about the gas and bloating…..to be continued.

  9. J. David Auner
    Springfield, MO, USA
    Reply

    The elderly are usually a special group. In the case of metformin, the life threatening adverse reaction of lactic acidosis occurs almost exclusively in excessive doses and with declining renal function. Most of the diabetes experts I queried 10 years ago did not have any patients over 70 on metformin. Yearly renal function testing is likely to be inadequate to protect people over 70, those with intercurrent illnesses and with the addition of any new chronic and some short term medications. Diabetics over 70 are, in my experience, fairly likely to suffer declines in their renal function.

  10. La Donna
    Nebraska
    Reply

    I take 250mgs. of metformin in the morning. I always have a stomach ache all day except
    feel better in the evening. I don’t know if it could be the metformin or what. I watch what
    I eat and drink only water. Does anyone have any ideas on this subject? I quit taking the
    metformin for awhile but still had stomach aches. Could it possibly take a few days for
    the metformin to get out of my system. I also have burning pains in my arms and stomach.

  11. Carole
    Sydney, NSW Australia
    Reply

    You didn’t mention Metformin as a PRO-pregnancy drug. Seems to do something for PCOS and to work like a ketogenic diet for low fertility. This was first noted about 10 years ago. I printed out the info then and gave it to a woman wanting to get pregnant Non-Diabetic and now I have a baby named after me!

  12. george
    home
    Reply

    here

  13. JIM
    CENTRAL NY
    Reply

    Been taking metformin since 2010, when the doctors office did a ‘whoops’ and gave me diabetes. So much for medical records, only good if the doctors read them.

    The side effects were bad for a while, but in using research from the Peoples Pharmacy and other sources, found my main problem was Generic metformin. My uncle, who is a Swiss doctor told me NEVER use generics. Now on the real Glucophage and almost all of the side effects are gone. My numbers have dropped and not having the foot problems anymore. Drugs effect people differently.

    • SUSAN
      Cleveland, OH
      Reply

      Jim, I had the same experience as you did. Metformin made me terribly nauseated, so I did some research which pointed toward Glucophage not causing any side effects. Long story short, after arguing back and forth with my PCP who stated there was no difference between metformin and Glucophage, he finally agreed to prescribe Glucophage. I’ve been on it for two months, and I’ve had NO adverse side effects. My A1C dropped from 8.7 to 6.8 in these two months, and I feel so much better.

  14. Robyn
    Central VA
    Reply

    I have chronic Lyme disease, which has messed up many things for me, including raising my A1C levels. Medical science is beginning to think that diabetes, and many other diseases, is caused by inflammation. Do what you can to lower your body’s overall inflammation load. Also read about non prescription ideas such as juicing bitter melon (found at Asian grocery stores and occasionally, Whole Foods) to lower your sugar levels. I found this to be very effective. Make sure you tell your doctor about any changes you make. Regular doctors will probably balk at the idea of bitter melon, but find an integrative or functional medicine doctor who will support you.

  15. bella
    ecuador
    Reply

    I live here in Ecuador even though I’m english speaking, after being told I am diabetec with stage 2, I started taking Metaformin 500mg. Wow to me it was too much went through a lot of pain in my liver stomach heart and kidneys, felt like throwing up, my feet hurt even more than before, so I started taking half a tablet of the 500mg but I still go through this pain I dont know why can someone please tell me.

  16. abbey
    canada
    Reply

    I have been on metformin for about 16 years or so, for the past year I’ve had Uti infections….at first the dr refused to admit something was wrong…..I’ve tried EVERYTGHING….I am wondering now if its metformin that has messed things up it’s the only link here….(i’m not telling people who need this med not to take it, (I’m not diabetic I have pcos) I’m saying READ up on it before taking it! side effect might out weigh EVERYTHING eles and it might not be right for you (you know when you see the ads on tv and the side effects are worse then what the goods are) be very careful with what you take…(the dr did a scan of my kidneys and never called back so I assume things are ok.

    • Mary
      Reply

      Abbey,
      I would ask my doctor for the written results of the tests taken. Don’t be in the dark.

  17. Dinty
    Central Connecticut
    Reply

    I’ve been metformin for a month and sugar readings are better. However, I started taking Cinnamon Bark oil which reportedly lowers blood sugar. Goal is to get off the Met.

  18. Anne
    NE
    Reply

    I have just worked up to 1500mg a day of Metformin xr.
    Everything was fine at 1000mg, but this last 500 is causing side effects… stomach hurting and acid reflux. I am going to hang in here for a week, before I go back to 1000. I really want to give it a chance.

  19. John
    Ohio
    Reply

    I think I’m an unusual type 2. I’m 71 yo, with an A1c of 8.4. I’m a competitive runner, very active, 5-10, 159 lbs, perfect health (except the A1c), don’t take ANY prescription meds, and I eat carefully I probably drink too much, 2-3 beers a day, but it’s all light beer with low carbs.

    No matter how hard I work out/run I can’t seem to get the A1c under control. In fact, after a hard run (5K, 28:00) my blood sugar spikes to 200-225.

    All diabetes diets start off telling you to get more active and lose weight. That clearly isn’t what I need.

    Any thoughts or observations would be greatly appreciated. Thanks!

    • HelenM
      Modesto, CA
      Reply

      Don’t know if you set yourself up to receive replies: you might have type 1 diabetes, treated only with insulin. Your age does not make it impossible. There is a variant of type 1 that affects adults. Initials are LADA, latent autoimmune diabetes in adults, and it has a much slower onset than type 1 diabetes in youths. There is a test they can do for certain anti-bodies (GAD) which can confirm this. Type 1 diabetics usually do not have the weight issues of type 2. While it is not associated with metabolic syndrome, you can have the same kind of complications. For your health’s sake, I would suggest a more aggressive follow up of this problem; hopefully with an endocrinologist, or a diabetologist, if you can find one.

    • Marty
      Glencoe, iL
      Reply

      Hi john
      Wow I have just received my first a1c report 8.4
      I was diagnosed with type 2
      I also exercise daily. 500-750 laps on pool daily. Walks up to 15 mikes. Weigh 188 5’10. I was told its biological. What have you heard?
      Regards Marty

  20. May
    Gresham, OR
    Reply

    My doc recently prescribed Metformin for Type II diabetes, and I was very pleased when the blood sugar was better controlled than it had been.
    Fortunately, though, she had ordered lab work as she does on a regular basis. It showed that my potassium level was too high. She had me stop taking the Metformin & a blood pressure med that contains potassium, and it got back to normal. I shudder to think what could have happened without that lab work. And I’m glad my doc realized what had caused the increase in potassium.

    • Devon
      New York
      Reply

      All I can say is that I sympathize and was having similar issues even on Bydureon weekly injections and the once daily Invokana pill (100mgs to start for a month). I was having terrible trouble with the dawn phenomenon–fasting blood sugars going up to 180 occasionally, and I wasn’t eating more than 30 carbs a day.

      I decided to add Metformin even though I know I can’t tolerate the gas and bloating–and feeling PREGNANT, which you may not experience. GRIN! BUT—my blood sugars have stayed between 90 and 95 ever since. I am, however, absolutely miserable from bloating as soon as I take the pill (only 500 mgs). I have started taking it at night so I will swell up when no one will see me.

      I am calling my doctor tomorrow about starting the XR variety instead. I can attest that your A1C will certainly go down as it sounds that you, like me, may have a liver that is throwing too much sugar into your system regardless of what you eat. Metformin counters that effect beautifully. BUT OH THE TUMMY woes….

      Good luck!

    • Elisha M.
      Hamlet, North Carolina
      Reply

      I have been taking metformin now for almost two full years. I started out with my blood sugar spiking up to 890. I have been in the hospital twice for blood sugar spikes. My a1c at its height was a 10 got it down gradually to a 7.2 as well my weight dropped from 245 lbs to 185 lbs. I feel as though my eating habits, faith and fear directly contributed to the weight loss and the lowered a1c. I have to take this with more severity though my weight has gone back up to 210 lbs I think my a1c has climbed back up to 8. So I’m looking back in order to move forward my eating habits were mainly raisin bran cereal with no high fructose corn syrup, salads with lots of grilled chicken without dressing. See you all on the healthy side.

What Do You Think?

We invite you to share your thoughts with others, but remember that our comment section is a public forum. Please do not use your full first and last name if you want to keep details of your medical history anonymous. A first name and last initial or a pseudonym is acceptable. Advice from other commenters on this website is not a substitute for medical attention. Do not stop any medicine without checking with the prescriber. Stopping medication suddenly could result in serious harm. We expect comments to be civil in tone and language. By commenting, you agree to abide by our commenting policy and website terms & conditions. Comments that do not follow these policies will not be posted.