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Metformin Reduces Hospitalizations Associated with Heart Failure

Jan 4, 2020
Editor: Steve Freed, R.PH., CDE

Author: Jordan Boyd, PharmD. Candidate Florida Agricultural & Mechanical University School of Pharmacy

Metformin reduces hospitalizations associated with heart failure, according to recent research on  the drug — one of the oldest antihyperglycemic drugs still in practice.

Patients with type 2 diabetes are often at risk of developing serious comorbidities as their diabetes progresses. One of the common comorbidities observed in patients with diabetes is heart failure. As the incidence of heart failure among the diabetes population continues to climb, strategies to decrease the hospitalization of these patients are being explored. A retrospective cohort analysis study was conducted by Dr. Chin-Hsaio Tseng to prove that early initiation of metformin for diabetes patients can be beneficial in preventing future hospitalization and exacerbations of heart failure. The study was funded by the Ministry of Science and Technology as well as the National Science Council. While a previous landmark trial (UK Prospective Diabetes Study) reported favorable cardiovascular outcomes associated with metformin, the drug’s actual effect on heart failure could not be demonstrated because of the small amount of heart failure patients included in the study. There were also several meta-analyses previously conducted, which reported that metformin had a neutral effect on heart failure. Unlike  Dr. Tseng’s study, these studies did not evaluate heart failure as a primary endpoint.


The major purpose of this study was to evaluate whether or not the use of metformin in diabetes patients can lower the risk of hospitalization for patients also diagnosed with heart failure. The study was a population-based retrospective cohort study which utilized Taiwan’s nationwide administrative database. At the beginning of data collection for the study, 423,949 newly diagnosed diabetes patients were prescribed two or more antihyperglycemics. From this pool, several groups of patients were excluded. The excluded patients included those who had received other agents before metformin, type 1 diabetes patients, and patients diagnosed with HF before a diabetes diagnosis. After these exclusions, 172,542 metformin users and 43,744 non-metformin users were identified. From here, a matched-pairs cohort was created with each group containing 41,714 patients. Statistical analysis was conducted on both unmatched cohorts as well as the newly created matched cohort. The Student t-test compared baseline characteristics. Patients’ cumulative duration of their metformin therapy was calculated in months. Cox models and regression were used primarily as main analysis tools.

The results from the study consistently exhibited a lower risk of heart failure associated with hospitalization in those patients who used metformin. Certain confounding variables were eliminated before calculations were complete. The overall risk reduction in the cohort that was unmatched was 65%, and 43% in the matched cohort. The group that used metformin for greater than 29.5 months showed a significantly reduced risk. In this study, age was a continuous variable and was divided into two subgroups. Confidence interval and P-value for all stratified groups were measured to be 95% and <0.0001 respectably.

This is the first study of its kind that was able to demonstrate a reduced risk of heart failure associated with hospitalization in type 2 diabetes patients on metformin. The most significant benefit with relation to this endpoint was observed when patients had been on metformin for 2.5 years or more. This study reinforces the assertion that metformin is a novel first-line agent for patients with type 2 diabetes mellitus, as it has now been shown to have benefits for patients with heart failure. Metformin is cost-efficient and very unlikely to cause hypoglycemic episodes when used as monotherapy. It is an oldie but a goodie that continues to prove why it has continued to be a mainstay in diabetes therapy for so long.

Practice Pearls:

  • Metformin should be considered as the first-line in all newly diagnosed type 2 diabetes patients because it is inexpensive and has shown some cardiovascular benefits as well as benefits in heart failure.
  • Early initiation of metformin in patients with type 2 diabetes can help decrease the occurrence of hospitalization associated with heart failure.
  • All efforts should be made to prevent patients from developing comorbidities associated with diabetes.

References for “Metformin Reduces Hospitalizations Associated with Heart Failure”:
Tseng CH. Metformin Use Is Associated With a Lower Risk of Hospitalization for Heart Failure in Patients With Type 2 Diabetes Mellitus: a Retrospective Cohort Analysis. Journal of the American Heart Association. 2019;8(21). DOI:10.1161/jaha.118.011640.

UK Prospective Diabetes Study (UKPDS) Group. Effect of intensive blood-glucose control with metformin on complications in overweight patients with type 2 diabetes (UKPDS 34). Lancet. 1998;352:854–865.

Jordan Boyd, PharmD. Candidate of Florida Agricultural & Mechanical University School of Pharmacy


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