Metformin lactic acidosis: Should we still be afraid?

Area of Science:

• Pharmacology and Endocrinology
• Diabetology
• Nephrology
• Cardiology
• Hepatology

Background:

• Metformin is a first-line treatment for type 2 diabetes, widely prescribed globally.
• Lactic acidosis (LA) is a rare but serious adverse effect associated with metformin.
• Concerns about LA have led to contraindications in patients with kidney, heart, and liver disease, potentially limiting metformin's use.

Purpose of the Study:

• To review the current evidence regarding metformin's safety and efficacy in patients with comorbidities.
• To re-evaluate historical contraindications for metformin use.
• To highlight emerging evidence on metformin's potential benefits beyond glycemic control.

Main Methods:

• Literature review of recent studies and clinical evidence.
• Analysis of data concerning metformin's effects on kidney, heart, and liver function.
• Examination of studies investigating the incidence and risk factors for metformin-associated lactic acidosis.

Main Results:

• Recent evidence suggests that historical contraindications for metformin use in patients with kidney, heart, and liver disease may be overly cautious.
• Studies indicate a potential protective effect of metformin (a biguanide) on the kidney, heart, and liver.
• The incidence of lactic acidosis is low and not solely attributable to metformin administration; some evidence even suggests a protective role against LA.

Conclusions:

• Contraindications and precautions for metformin use should be re-evaluated based on current evidence.
• Reducing overly strict precautions can allow more diabetic patients, including those with comorbidities, to benefit from metformin.
• Metformin's potential benefits in various conditions beyond diabetes warrant further investigation and should not be hindered by outdated safety concerns.