Metformin May Be a Drain on the Brain

Increased Risk of Cognitive Impairment in Patients With Diabetes Is Associated With Metformin. By Eileen M. Moore and colleagues. Diabetes Care 2013;36:2981–2987

What is the problem and what is known about it so far?

People with type 2 diabetes are at an increased risk for developing cognitive disorders, such as Alzheimer disease. Metformin is one of the most common type 2 diabetes medications, and it is often the first medication prescribed after diagnosis. Studies have shown that metformin use is linked to vitamin B12 deficiency, which may negatively affect the brain. Calcium supplements have been shown to reverse metformin-linked B12 deficiency.

Why did the researchers do this particular study?

The researchers wanted to learn what connections, if any, exist between brain function, metformin, vitamin B12 levels, and calcium supplementation in people with diabetes.

Who was studied?

The study included 970 people in Australia, including those with cognitive impairment, Alzheimer disease, and diabetes.

How was the study done?

The researchers analyzed the health records of study participants to assess their history of metformin use and diabetic status. They gave participants an examination that assessed cognitive function within six months of a blood test that checked for B12 levels. The data was analyzed by statistical software to tease out correlations between health factors.

What did the researchers find?

People with diabetes had overall worse brain function than those without the disease. Among participants with diabetes, those taking metformin performed less well on the cognitive tests than those managing diabetes with other approaches. People with diabetes who used calcium supplements displayed better cognitive performance on average than those who did not.

What were the limitations of the study?

This study cannot prove metformin causes cognitive decline. Also, the study was too small to determine if there is any link between metformin dose or duration of use and cognitive function.

What are the implications of the study?

Vitamin B12 and calcium supplements may alleviate metformin-induced cognitive decline in people with diabetes.

  • Last Reviewed: January 15, 2014
  • Last Edited: January 15, 2014

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