galactose is a sugar found in milk. when combined with glucose (another sugar) it forms lactose.
for diabetics this may be bad as a supplement , as it is a sugar.
the body synthesizes what it needs, and the excess is discarded; it is not needed as a supplement except in very rare cases where the body cannot synthesize it; that usually manifests in infants as its a heredity trait (missing the enzyme to create galactose).
thusly this appears to be a scam. if you want more glactose drink more milk. if you are lactose intolerant, drink lactose free milk, which has an enzyme added to break down lactose into galactose and glucose. i do not recommend adding galactose to the diet of a diabetic; seek out a medical professional for advise on that.