Clinical Pearls: Metformin

Metformin is part of the biguanide class of diabetes meds – I don’t know why I told you that, because you will probably never need to know that, but I have been wrong before. Metformin is usually fairly well tolerated as long as you can avoid the GI symptoms. One of my pet peeves is when an elderly individual gets started on drugs that are notoriously bad for side effects when not tapered up slowly. I’ve seen cases where individuals get started on 1000 mg twice a day (a higher dose) and have stomach type side effects like nausea, maybe loose stools etc. and then get taken off the drug and it gets added to their intolerance list! Frustrating! They may not have tolerated it anyway, but now anyone will be hesitant to try it again, not knowing the background of the intolerance. In individuals with kidney disease, you want to take a close look to make sure this drug is appropriate – there is an elevated risk of lactic acidosis(very rare) in patients on metformin with poor kidney function. I’ve been asked the question a couple different times about B12 deficiency and metformin use. Clinically I have not seen this more than a couple times and it really seems to be very rare. If an individual does have symptoms of B12 deficiency like anemia, certainly it may be worthwhile to consider checking a B12 level and identify if supplementation should be required, but again, this is a very rare occurrence.

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  1. ma.PharmD

    oh!! rare!!!

    in our hospital ,they always give the Vit B12 as a supplements with Metformin without check the level of this vitamine

  2. Sheshagiri Gandasi

    This is a favourite hypoglycaemic agent amongst the Indian Doctors espcially the sustained release tablets as they shower good money to the prescriber and the Big Pharma alike!

    • Annek

      Metformin regular release is so cheap compared to most of the new diabetic agents. It is a good agent for diabetes as long as you don’t have kidney disease.

  3. Whitney

    At my hospital, when a patient is admitted they are taken off the metformin and switched to a sliding scale for: 0800/1200/1700/2100/0300. Is there a reason for this? Is it because we want tight control? I thought it was because patients may not be eating or may be npo before surgery. But I was told that it can’t drop your glucose to dangerous levels even if your not eating.



  1. Compelling Indications in Diabetes - Why to Choose Different Agents - Med Ed 101 - […] Metformin is going to be a first-line medication in type 2 diabetes (with a few rare exceptions). In younger…
  2. Medications Targeting Pre- and Post-Prandial Glucose: It Takes Two - Med Ed 101 - […] this mantra in mind when deciding where to start in Type 2 diabetes. Metformin is recommended as a first-line…
  3. when to start metformin in type 2 diabetes – Bnr.Co - […] Source: Clinical Pearls: Metformin – Med Ed 101 […]

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Written By Eric Christianson

November 22, 2013

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