# Metformin-Induced Hemolysis in a Glucose-6-Phosphate Dehydrogenase-Deficient Patient: A Case Report

## TL;DR

A patient with G6PD deficiency experienced a hemolytic crisis after taking metformin, highlighting the need for screening in high-risk groups.

## Contribution

This case report identifies metformin-induced hemolysis in a G6PD-deficient patient, emphasizing the importance of pre-treatment screening.

## Key findings

- A middle-aged man developed hemolytic crisis after metformin use and was found to have G6PD deficiency.
- Discontinuation of metformin and supportive care led to patient improvement.
- The case underscores the rare but significant risk of metformin in G6PD-deficient individuals.

## Abstract

Metformin is a first-line medication used in the treatment of type 2 diabetes mellitus along with other conditions such as insulin resistance and polycystic ovarian syndrome. Overall, metformin appears to be well tolerated with a low incidence of side effects; however, in certain high-risk populations, it can trigger a hemolytic crisis. This case report describes a middle-aged man who was initiated on metformin for new-onset diabetes, following which he had an acute hemoglobin drop and was diagnosed to be having a hemolytic crisis requiring hospitalization. He was diagnosed with a deficiency of the enzyme glucose-6-phosphate dehydrogenase (G6PD) on admission. Extensive workup was done to rule out other causes of hemolysis, all of which came back to be negative. The offending agent was stopped and the patient received supportive care after which he improved. This case highlights a rare, yet important, side effect of metformin that needs to be observed in certain individuals, especially patients with G6PD deficiency. Routine testing of high-risk populations known to be G6PD deficient should be considered before initiating metformin.