Metformin-Associated Vitamin B12 Deficiency: An Underrecognized Complication

Area of Science:

• Endocrinology
• Neurology
• Geriatrics

Background:

• Metformin is a common treatment for type 2 diabetes mellitus.
• Metformin-associated vitamin B12 deficiency is a known complication, particularly with long-term use or higher doses.
• Severe vitamin B12 deficiency can manifest with diverse systemic and neurological symptoms.

Observation:

• An 84-year-old male on long-term metformin presented with frequent falls and fatigue.
• Neurological examination revealed impaired vibratory sensation, proprioception, and a positive Romberg test.
• Investigations showed undetectable vitamin B12 and elevated homocysteine levels.

Findings:

• The patient was diagnosed with acute-on-chronic subdural hematoma secondary to falls, linked to metformin-induced vitamin B12 deficiency.
• Neurological symptoms improved rapidly following vitamin B12 replacement and surgical intervention.
• This case underscores the underrecognized link between metformin, B12 deficiency, falls, and subdural hematoma in the elderly.

Implications:

• Highlights the importance of considering vitamin B12 deficiency in older diabetic patients experiencing unexplained falls or neurological changes while on metformin.
• Emphasizes the need for regular monitoring of vitamin B12 levels in this patient population.
• Suggests that early detection and treatment of vitamin B12 deficiency can prevent serious complications such as subdural hematomas.