Metformin is the only biguanide, or hypoglycemia-inducing drug, approved in the United States for the treatment of type 2 diabetes, which is noninsulin dependent. Metformin is the preferred medication for newly diagnosed patients and is effective in controlling blood sugar levels. However, metformin may cause several side effects, such as affecting how vitamin B12 is absorbed by the body. Discuss any concerns about metformin and its side effects with your physician.
Metformin Function
Metformin decreases the production of glucose, or sugar, by the liver. It also leads to the breakdown and removal of glucose from the blood. Metformin prevents the complete absorption of glucose from the stomach and leads to decreased glucose levels in the body.
B12 Function
Vitamin B12 is water-soluble and found naturally in animal products, including fish, meat, poultry and dairy. It is required for the production of red blood cells and proper neurological function. A deficiency of B12 leads to weakness, fatigue, constipation, loss of balance, weight loss and other conditions.
Iron Function
Iron is a metal essential for proper cell function. It is an important part of proteins involved in the transport of oxygen throughout the body. Iron also helps to regulate cell growth and specialization of cells. A deficiency of iron results in fatigue as well as decreased work performance and immune function.
Metformin and B-12
Metformin may reduce the absorption of vitamin B12 in the body. About 10 to 30 percent of individuals who take metformin may experience a decrease in the absorption of B12, according to the Office of Dietary Supplements of the National Institutes of Health. This decrease is more likely to occur with long-term use of the medication.
Metformin and Iron
No interaction exists between metformin and iron, according to Drugs.com. If you are taking metformin and develop symptoms of an iron deficiency, contact your physician right away for further investigation.
Monitoring
Patients on metformin should be monitored regularly to ensure proper glucose control and to manage side effects. Vitamin B12 levels should be checked annually in patients taking metformin to determine if supplementation is necessary, according to "Basic and Clinical Pharmacology." Prescription-strength B12 usually is given by intramuscular injection. Although iron is not part of the monitoring parameters for metformin, your physician can check your iron level with a routine blood test. If your iron level is low, you physician can recommend an over-the-counter iron supplement.
References
- "Drug Information Handbook"; Charles F. Lacy, Lora L. Armstrong, et al.; 2009
- Drugs.com: Drug Interactions Between Elemental Iron and Metformin
- "Basic and Clinical Pharmacology"; Bertram G. Katzung; 2007
- Office of Dietary Supplements: Vitamin B12
- Office of Dietary Supplements: Iron
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