There was 298 participants and 202 were prescribed and consuming metformin. De Groot-Kamphuis and colleagues (2013) assessed the dosage of metformin, length of time of metformin use, and ***. Blood samples were taken and evaluated with a modular analyzer. They revealed that 14.1% of the participants who took metformin were B-12 deficient compare to 4.4% of the participants did not take metformin. The main variable that was significant was the dosage because for every 100mg increase of metformin, there was a decrease of about 3.77pmol/l (8%) in vitamin B-12