Take Metformin before or after surgery...Why?

  1. I was asked a question on my patho exam about a patient (type 2 diabetic) asking the nurse whether or not he should take his Metformin before or after surgery. I could not find any clear rationale to this question. The answer I chose was before surgery, thinking that since the patient was going for surgery he would be stress and therefore the body would produce a higher glucose level so by giving the patient the Metformin now, it could help keep his sugars in check throughout the surgery as apose if he would get it afterwards he could fall rise of becoming hyperglycemic...am I right or wrong? If you could explain what the best option is for the nurse to tell the patient, this would be very much appreciated.
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    About blue.streak

    Joined: Nov '11; Posts: 22; Likes: 1
    BScN Student; from CA


  3. by   Double-Helix
    Metformin should be held on the day of surgery for a couple of reasons: 1. There is concern with decreased renal function in the peri-operative period. This is actually the primary reason for stopping the medication. 2. The patient is not eating food. Yes, stress might raise insulin levels, but the patient may not be feeling enough stress to raise the blood sugar significantly. Remember that Metformin works over an extended period of time- about 12 hours. The risk of hypoglycemia when continuing Metformin while NPO is much greater than the risk of hyperglycemia from the stress response. The medication can be resumed after the surgery, when the patient is eating a normal diet again. In diabetic patients, the best way to control post-operative blood glucose when they are still NPO is with insulin.

    Here's one link that explains this. You can also type "Metformin before surgery" into Google and you'll get several other links that answer your question.

  4. by   Silverdragon102
    Also to mention before certain tests not just surgery is Metformin held

    eg Giving IV iodine contrast and also ?radiopaque
  5. by   CP2013
    Sorry to hijack this post, but a family member just had a surgery for varicose veins in his leg, where the veins were removed from the groin to the ankle in both legs I believe.

    They told him to take half of his regular metformin dose, as he does not use insulin.

    What would the rationale be for this then? Is it because they were planning on d/c approximately 4 hours post op? They sent him home the same day, and resumed eating and taking daily metformin.

    Diabetes is interesting for sure, it seems like while there are similarities among diabetics, they still are very much individuals! Always nice to be reminded of that. Thanks!
  6. by   blue.streak
    Thanks for the answers everyone!
  7. by   dragon_lady
    In Cardiac catheterization,metformin is witheld 48 hours prior to surgery because renal functions might alter,causes Lactic Acidosis.
  8. by   classicdame
    Metformin is frequently held for surgery and for admission due to all the reasons above. We can always adjust glucose with rapid acting insulin
  9. by   esha.tam
    Metformin is a biguanide which 1) decreases the production of glucose by the liver, 2) decreases intestinal absorption of glucose and 3) increases uptake of glucose by tissues by improving insulin receptor sensitivity. It does not increase insulin levels therefore it does not induce hypoglycemia in NPO patients (this is also why metformin is only given to type 2 diabetes and not type 1)

    Metformin has a high renal involvement, therefore it isnt given preoperatively to avoid renal impairement especially if the procedure requires a contrast medium. Upon return from the procedure, it is usually given. In certain cases, it is held post operatively as well to avoid lactic acid production in those who are at risk.

    So in general, metformin is usually held preoperatively and given posteoperatively.

    Hope that helps