The following research was a double-blind placebo controlled study which included patients diagnosed with the metabolic syndrome (Setola E, et.al., 2004).

Patients with metabolic syndrome are usually overweight, have insulin resistance and high blood pressure.

Treatment with vitamin B12 and folic acid for 1 month were compared with a placebo treatment.

The researchers found that folic acid and vitamin B12 treatment improved insulin resistance and endothelial dysfunction, and also decreased homocysteine levels.

Homocysteine is an amino acid which at higher levels will negatively affect endothelial function. The endothelium is the inner layer of the blood vessels.

This means the research showed improvements in both blood glucose control and cardiovascular function.

When you take folic acid be sure to take the metabolite since quite e few people does not absorb folic acid well.

Reference

Emanuela Setola, Lucilla Domenica Monti, Elena Galluccio, Altin Palloshi, Gabriele Fragasso, Rita Paroni, Fulvio Magni, Emilia Paola Sandoli, Pietro Lucotti, Sabrina Costa, Isabella Fermo, Marzia Galli-Kienle, Anna Origgi, Alberto Margonato, Piermarco Piatti, Insulin resistance and endothelial function are improved after folate and vitamin B12 therapy in patients with metabolic syndrome: relationship between homocysteine levels and hyperinsulinemia, Eur J Endocrinol. 2004 Oct;151(4):483-9.