Unusual Case of Metformin-Associated Lactic Acidosis in Patient with Type 2 Diabetes Mellitus

Metformin-Associated Lactic Acidosis in an Older Adult: A Case Report and Review

Metformin is a widely prescribed medication for the management of type 2 diabetes. It is known to have a high safety index; however, it can cause serious adverse effects such as lactic acidosis, particularly in patients with chronic kidney disease. Elderly patients are at higher risk of developing metformin-associated lactic acidosis (MALA) due to aging kidneys. We present an 82-year-old male with a past medical history of diabetes, stage 2 chronic kidney disease, atrial fibrillation on apixaban, stroke, and chronic stage 4 sacral decubitus ulcer who was sent to the emergency department (ED) for altered mental status. He was admitted to the intensive care unit for the management of septic shock, pulseless electrical activity (PEA) cardiac arrest, and acute hypoxemic respiratory failure requiring intubation. Laboratory tests showed lactic acidosis and anion gap metabolic acidosis in the absence of an infectious source. The patient had chronic kidney disease with acute renal failure on metformin. He was diagnosed with MALA. This case highlights the potential risks associated with metformin use in older adults with chronic kidney disease and acute kidney injury from infections, dehydration, and decreasing oral intake due to acute illness, aging, or dementia. There are expected physiological changes in the aging kidney, including cellular dysfunction and nephrosclerosis, that can cause unexpected kidney injury in older adults, causing their estimated glomerular filtration rate (eGFR) to drop acutely. Age-related changes in renal function and decreased clearance of drugs place elderly patients at higher risk of developing MALA. Guidelines for reducing or deprescribing metformin can be considered in older adults. This could prevent morbidity, mortality, and adverse outcomes in frail older adults with diabetes.

Metformin adverse event profile: a pharmacovigilance study based on the FDA Adverse Event Reporting System (FAERS) from 2004 to 2022

BACKGROUND

Metformin has the potential for treating numerous diseases, but there are still many unrecognized and unreported adverse events (AEs).

METHODS

We selected data from the United States FDA Adverse Event Reporting System (FAERS) database from the first quarter (Q1) of 2004 to the fourth quarter (Q4) of 2022 for disproportionality analysis to assess the association between metformin and related adverse events.

RESULTS

In this study 10,500,295 case reports were collected from the FAERS database, of which 56,674 adverse events related to metformin were reported. A total of 643 preferred terms (PTs) and 27 system organ classes (SOCs) that were significant disproportionality conforming to the four algorithms simultaneously were included. The SOCs included metabolic and nutritional disorders (p = 0.00E + 00), gastrointestinal disorders (p = 0.00E + 00) and others. PT levels were screened for adverse drug reaction (ADR) signals such as acute pancreatitis (p = 0.00E + 00), melas syndrome, pemphigoid (p = 0.00E + 00), skin eruption (p = 0.00E + 00) and drug exposure during pregnancy (p = 0.00E + 00).

CONCLUSION

Most of our results were consistent with the specification, but some new signals of adverse reactions such as acute pancreatitis were not included. Therefore, further studies are needed to validate unlabeled adverse reactions and provide important support for clinical monitoring and risk identification of metformin.