But this is no campaign ad. It is an Internet infomercial for a dubious diabetes treatment, in which Mr. Huckabee, who is contemplating a run for the Republican nomination in 2016, tells viewers to ignore “Big Pharma” and instead points them to a “weird spice, kitchen-cabinet cure,” consisting of dietary supplements. “Let me tell you, diabetes can be reversed,” Mr. Huckabee says. “I should know because I did it. Today you can, too.”