Both sulforaphane and metformin reduce glucose production by the liver, through a mechanism the body uses to ensure it has enough fuel during periods of fasting, like overnight. In diabetics who are also overweight, Rosengren said, the liver's glucose production function is not sensitive to the body's needs, and the liver dumps too much glucose into the bloodstream, causing unhealthy spikes in blood sugar levels.
Source: tatoeba (12250911)