It has asked once and it won't ask again: the Food and Drug Administration announced Tuesday that it had issued letters to 15 companies whose sale of illegally marketed diabetes products it says violates federal laws.

The companies included both foreign and domestic entities whose products were sold online and in retail stores.

In the meantime, the U.S. agency is advising consumers not to use these or similar products due to the possibility of harmful ingredients or other possible risks involved.

The products, the FDA reports, may be improperly marketed as over-the-counter products when they should be marketed as prescription products and could cause consumers to delay seeking proper medical treatment for their illness.

They include:

  •  Products sold as "natural" treatments for diabetes, but contain undeclared active pharmaceutical ingredients in unknown quantities that could cause harm or complicate medical conditions;
  •  Dietary supplements and ayurvedic products (a form of medicine that originated in India) with claims to treat, cure and/or prevent diabetes;
  •  Unapproved drugs sold over-the-counter, including some homeopathic products, intended to treat complications associated with diabetes, including relieving symptoms caused by nerve damage in the arms and legs (also called peripheral neuropathy); and
  •  Prescription drugs for diabetes sold by online pharmacies without a prescription.

"Diabetes is a serious chronic condition that should be properly managed using safe and effective FDA-approved treatments," said FDA Commissioner Dr. Margaret A. Hamburg. "Consumers who buy violative products that claim to be treatments are not only putting themselves at risk but also may not be seeking necessary medical attention, which could affect their diabetes management."

Nearly 26 million Americans live with diabetes, a disease in which blood glucose or blood sugar levels are high due to the body's inability to produce sufficient amounts of insulin or to effectively utilize its own insulin.

Greater health risks associated with diabetes include heart disease, blindness, kidney failure and lower-extremity amputations if not managed properly.

"The FDA is committed to protecting consumers from the dangers of these illegally sold products," said Howard Sklamberg, director of the Office of Compliance in the FDA's Center for Drug Evaluation and Research. "We will continue to take aggressive action against firms that sell illegal products claiming to treat diabetes."

To date, however, the agency reports that it is not aware of any reports of injury or illness associated with the products, but encourages those who believe they have been affected to contact it here.