Broccoli sprout extract reduced HbA1c by 7.04% in obese patients with dysregulated type 2 diabetes. It has been demonstrated that a 1% decrease of HbA1c corresponds to 37% reduced risk of microvascular complications.

Sulforaphane reduces glucose by suppressing liver enzymes that otherwise stimulate the production of glucose.

In animals, sulforaphane also attenuated exaggerated glucose production and glucose intolerance by a magnitude similar to that of metformin.

Further investigations showed that while both metformin and sulphoraphane cut blood glucose, they do it in different ways. Metformin makes cells more sensitive to insulin, so they sponge more surplus glucose out of the bloodstream. Sulphoraphane reduces glucose by suppressing liver enzymes that otherwise stimulate the production of glucose. For this reason, Rosengren thinks the broccoli extract is complementary to metformin, not competitive."