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Metformin Reduces Presurgical Stress 

Aug 22, 2020
Editor: David L. Joffe, BSPharm, CDE, FACA

Author: Zahra Hashemy, PharmD. Candidate, USF Taneja College of Pharmacy

Presurgical metformin was used to reduce the risk of complications associated with surgery in type 2 diabetes patients. 

Surgical procedures are usually very stressful for patient homeostasis, as the body is placed under a considerable strain, and higher stress level is associated with an increased risk of morbidity and mortality. Research was done by JAMA to determine the effectiveness of metformin use before surgeries to reduce the risk of complications in patients with type 2 diabetes. Metformin is the most common medication to manage patients with prediabetes or type 2 diabetes. Patients with type 2 diabetes usually show a higher rate of surgical intervention than patients at the same age without type 2 diabetes. They also show a higher risk of readmission because of hyperglycemia at the time of surgery, reduced leukocyte formation, and wound healing.  


The study was done by Dr. Katherine M. Reitz and her team to test the efficacy of using metformin pre-surgery to lower the risk of readmission, morbidity, and mortality. Type 2 diabetes is prevalent in the United States. Especially in patients older than 65, almost half of type 2 diabetes patients will need surgical intervention. Due to the increased risk of complications resulting from diabetes, cardiovascular, neuropathic, nephrotic, and even ocular complications may not be resolved only by pharmacological treatment and may need surgical intervention. Diabetes impairs the body’s ability to reduce inflammation, which is extremely important after surgery. The lack of inflammatory reserve in patients with diabetes would lead to further complications and longer admission times.  

The team used electronic records to identify patients with type 2 diabetes who underwent surgical intervention. 59% were administered metformin before the start of the surgery. The researchers linked the effectiveness of the use of metformin to its anti-inflammatory properties. The mean age of patients in the study was 67.7 years, and the number of subjects was equally distributed among genders. One of the benefits of the study is that it included many subjects, consisting of almost 100,000 patients divided into metformin taking and non-metformin taking groups. 

The level of inflammation was evaluated using neutrophil-to-leukocyte ratio, comparing the values in patients receiving metformin and patients not receiving metformin preoperatively. The absolute risk reduction (ARR) and adjusted hazard ratio (HR) with 95% CI have been calculated in the propensity score-matched cohort. According to the values, it was proven that metformin reduces the risk of morbidity and mortality in type 2 diabetes patients undergoing surgery. Mean neutrophil to leukocyte ratio, 4.5 [95% CI, 4.3-4.6] compared with 5.0 [95% CI, 4.8-5.3]; P <.001.  

After evaluating efficacy data, the research team analyzed readmission rates within 90 days of discharge in addition to mortality rates, and patients that were administered metformin had a lower hazard for 90-day mortality (adjusted HR, 0.72 [95% CI, 0.55-0.95]; ARR, 1.28% [95% CI, 0.26-2.31]), and hazard of readmission, with mortality reported as a competing risk at both 30 and 90 days, (ARR, 2.09% [95% CI, 0.35-3.82] and ARR, 2.78% [95% CI, 0.62-4.95]), respectively. Overall, metformin use reduced the risk of readmission, mortality, and multiple complications that occur postoperatively.  

The authors of the study concluded that the benefit of using metformin might not be diseasespecific. Similar results will be obtained if metformin is used in non- diabetic patients due to metformins ability to reduce inflammation and stress caused by major surgical procedures. The study did not include the procedures performed, because metformin showed an improvement in all aspects regardless of the type of surgery. It was apparent that metformin reduced all-cause mortality and complications associated with surgical procedures in patients with type 2 diabetes. Although the study showed clinical and statistical significance, it requires further evaluation to demonstrate the safety outcomes associated with metformin use.  

Due to a lack of safety reports, the use of metformin is not recommended in any guidelines for presurgical prevention in patients with diabetes. The study was clinically significant and included a tremendous power and fair distribution of the subjects, proving that the use of metformin was beneficial in all cases regardless of age or gender.  

Practice pearls:   

  • Metformin showed benefit in patients undergoing major surgeries. 
  • Metformin was shown to-be anti-inflammatory and help with shortening the duration of the healing time. 
  • Metformin administration needs further studies to be in the guidelines for additional prophylaxis. 


Staff. Presurgical Metformin Use Is Improving Outcomes. US Pharmacist – The Leading Journal in Pharmacy, June 16, 2020, www.uspharmacist.com/article/presurgical-metformin-use-is-improving-outcomes. 

Zahra Hashemy, PharmD. Candidate, USF Taneja College of Pharmacy 


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