Endocrine Abstracts

Introduction: Metformin, the primary treatment for type 2 diabetes, is renowned for its positive effects on carbohydrate metabolism, weight management, and vascular health. Despite these well-established benefits, prolonged use of metformin has been linked to potential adverse reactions, including a decrease in serum vitamin B12 levels and the development of anemia¹. This case further emphasizes the complexities associated with metformin use by introducing an unusual yet consequential complication: severe neurological manifestations stemming from vitamin B12 deficiency.

Case Report: We present an intriguing case involving a 64-year-old woman managing type 2 diabetes through the extended use of insulin analogs, vildagliptin, and metformin. The patient exhibited a frontal syndrome, progressive gait instability, cognitive disruptions, frequent falls, and paroxysmal episodes associated with urinary incontinence. Thorough investigations, including normal imaging and a temporal artery biopsy excluding inflammatory origins, were conducted. The electroencephalogram revealed moderate diffuse cerebral distress with a metabolic component. Despite the absence of dietary deficiencies, gastric surgery, or Biermer’s disease, a significant vitamin B12 deficiency was identified at 50 pg/ml. A meticulous examination uncovered a connection between extended metformin use and the observed vitamin B12 deficit. Following intramuscular vitamin B12 supplementation and discontinuation of metformin, despite the authors’ suggestion to "search, treat the deficiency, and continue metformin"² we decided to discontinue it due to the absence of clear directives. The subsequent progress yielded positive outcomes, including symptom regression, the restoration of normal ambulation, and the resumption of daily activities, accompanied by the normalization of vitamin B12 levels.

Conclusion: This case highlights the critical importance of regular monitoring for individuals on metformin, especially those with identifiable risk factors, underscoring the potential for vitamin B12 deficiency. The intricate relationship between metformin and vitamin B12 deficiency necessitates continuous scrutiny and consideration in clinical practice. This emphasizes the need for heightened awareness and vigilance in managing complications related to diabetes.

References: 1. The American Diabetes Association Releases the Standards of Care in Diabetes—2024 [Internet]. [cité 21 janv 2024]. Disponible sur: https://diabetes.org/newsroom/press-releases/american-diabetes-association-releases-standards-care-diabetes-2024. 2. Davies S. Metformin use and vitamin B12 deficiency: New MHRA guidance. 26(5).