The short answer is yes. Out of curiosity, I looked it up online quickly and there were tons of links that popped up saying " According to some studies, between 10% and 30% of people who take metformin on a regular basis have some evidence of decreased B12 absorption. Researchers aren’t quite sure why this happens. In a study recently published in the October 9 issue of the journal Archives of Internal Medicine,155 Chinese people with Type 2 diabetes taking metformin were identified as having a B12 deficiency, regardless of factors such as age or body weight. The study found that the longer a person had been taking metformin and the higher his daily dose of the drug, the greater his risk of developing B12 deficiency.
The authors of the study advocate consideration of vitamin B12 deficiency screening for people who take metformin."
Although they don't list the studies, this information is consistent on several sites. Here's one:
www.diabetesselfmanagement.com/blog/metformin-and-risk-for-vitamin-b12-deficiency/