The Food and Drug Administration (FDA) has sent warning letters to 15 companies urging them to stop selling treatments which violate U.S. laws and also may cause harm to diabetes patients — leading to complications like heart disease or kidney failure. Because diabetes affects such a large number of the American population, the companies marketing illegal treatment for the disease aim to cash in on the epidemic — labeling dietary supplements and prescription drugs as diabetes medication without getting it approved by the FDA.

In the U.S., diabetes afflicts nearly 26 million Americans and 8.3 percent of the population, and can cause premature death, blindness, kidney failure, and limb amputations. It was ranked as the seventh leading cause of death in the U.S. in 2007. According to the Centers for Disease Control and Prevention (CDC), one in three adults will have diabetes by 2050 if the current trends continue.

The FDA urged consumers to be more cautious before buying these so-called "all-natural" products, stating that they are "unsafe and should not be used."

Recently, the FDA has been cracking down on rogue internet pharmacies that sell cheap, but unregulated, drugs online. In June 2013, over 1,600 online pharmacies operating in an organized crime network were shut down, becoming the largest Internet-based enforcement action.

One of the companies that received a letter from the FDA regarding unregulated diabetes drugs was Hi-Tech Pharmacal Co., located in Amityville, New York. The company, which generates about $232 million yearly in sales, agreed to remove the three over-the-counter creams that it had claimed would be beneficial to diabetes patients.

The three creams, Diabeti-Derm Antifungal Cream, Zostrix Diabetic Foot Pain Relief Cream, and Diabetic Joint & Arthritis Pain Relief Cream, generated about $1.1 million for the company in one year. Hi-Tech Pharmacal admitted that they would need to adjust the titles of these creams based on the FDA's warning.

As the number of people with diabetes continues to rise (the number of adults with diabetes has increased by 45 percent in the past 20 years), so does the market for prescription diabetes drugs. Sales that were once at $13.8 billion in 2008 have risen to $22 billion in 2012, according to IMS Health.

"People with chronic or incurable diseases may feel desperate and become easy prey," National Health Fraud Coordinator Gary Coody said in a statement. "Bogus products for diabetes are particularly troubling because there are effective options available to help manage this serious disease rather than exposing patients to unproven and risky products."

On its website, the FDA warns consumers to notice red flag phrases such as, "Lowers your blood sugar naturally," "Protects your eyes, kidneys, and blood vessels from damage," and "Replaces your diabetes medicine."

Adjusting exercise and food habits, as well as keeping an eye on blood sugar levels, are more effective and safe routes than buying into risky online treatments.

"Products that promise an easy fix might be alluring, but consumers are gambling with their health," Coody said.