Control your blood sugar with a supplement?

"If you are a diabetic and concerned about maintaining your healthy blood glucose levels, stay tuned for this important message," begins a recent television advertisement touting the $50-per-month (plus shipping and handling) dietary supplement Glymetrol. "Clinical studies of the key ingredients in Glymetrol have shown these ingredients to be effective in supporting healthy glucose management."

But have studies really proved that the many ingredients in Glymetrol—which include alpha lipoic acid, American ginseng, chromium, cinnamon extract, nopal cactus, and zinc—are effective in supporting healthy blood glucose in people with diabetes, as the advertisement suggests? Simply put, no.

"There is not enough evidence to prove that dietary supplements have substantial benefits for type 2 diabetes or its complications," according to the National Institutes of Health's National Center for Complementary and Alternative Medicine, which compiles scientific research on nonconventional medicines. What scant research exists has found limited blood-sugar-lowering abilities for some of the ingredients, particularly alpha lipoic acid (available to subscribers), chromium (available to subscribers), and nopal cactus. But evidence is inconsistent, and it doesn't appear that the ingredients have been tested together. And if they do work, some ingredients might actually lower blood sugar too much.

Bottom line. Although Glymetrol's website includes a disclaimer that the supplement "is not intended to diagnose, treat, cure or prevent any disease," it also touts Glymetrol as a "revolutionary breakthrough in natural blood-sugar management." For people with diabetes, who need medications proved to manage their blood glucose levels, that could be a dangerous promise. If you decide that you want to complement conventional medicine with a supplement, consult your doctor. And before you order Glymetrol, note that the company has an "F" rating from the Better Business Bureau due to reports of "unanswered complaints."