If you are a diabetic and have been taking metformin for at least one year, you need to check your b12 level. There is an associated risk of b12 deficiency. This does not mean you stop taking your metformin. Metformin is an excellent diabetic medication that can effectively and safely manage your type 2 diabetes. It has an excellent safety record.
The mechanism for the possible lower b12 level is decreased absorption. Calcium malabsorption (poor absorption) may also contribute. It has been shown that calcium supplementation may help to decrease the induced b12 malabsorption. Just how common this is in not known. Research is underway regarding the clinical or medical significance.
It is recommended that you have a b12 (cobalamin) level checked once per year when taking metformin. If your level is low, then discuss b12 supplementation with your healthcare provider. A quality sublingual supplement is usually adequate. This supplement should include the B complex vitamins such as B1 (Thiamin), B2 (Riboflavin), B3 (Niacin), and B6 (Pyridoxine) which are necessary for good absorption of B12. Folate is also a necessary ingredient of a quality supplement.
If calcium supplementation is recommended, consider taking a quality / certified pure coral calcium supplement. Certified pure means that correct methods of harvesting the calcium from coral have been followed and the unsafe heavy metals such as lead, mercury, and aluminum have been removed.
Below are some recommended medical articles:
1. Bauman WA, Shaw S, Jayatilleke K, Spungen AM, Herbert V. Increased intake of calcium reverses the B12 malabsorption induced by metformin. Diabetes Care 2000;23:1227-31.
2. Andrès E, Noel E, Goichot B. Metformin-associated vitamin B12 deficiency. Arch Intern Med 2002;162:2251-2.
3. Bagree R, Gibby OM, Penney MD, Lloyd HH. Prevalence of vit.B12 deficiency with metformin treatment. Diabetic Med 1999;16(suppl 1):P61.