In 1994, eight-year-old Zoe Burbridge went to bed in the town of Northampton, England, and never woke up. In 2002, 15-year-old Selina Trapp, from Derby, also in the United Kingdom, died in her sleep. Two years earlier, an American, 49-year-old Susan Mescher from Lexington, Michigan, had slumped over in the shower, never to regain consciousness.

These individuals were just a few of the hundreds of diabetics who suddenly died between 1983 and 2002. Medical examiners attributed their deaths to complications related to the condition, such as cardiovascular problems, but they all had something else in common at the time of death: every one of them had recently switched from animal to genetically engineered insulin.

Since the development of insulin therapy in the early 1920s, more than half a century after the initial discovery of the hormone, diabetics had used porcine or bovine insulin made by multinationals Eli Lilly or Novo Nordisk, or domestic companies. These formulas were generally safe and effective, but could not be manufactured on a mass scale.

Determined to capture a global market at a time when worldwide insulin sales—which stood in 1982 at $400 million—were expected to double, both Eli Lilly and Novo Nordisk invested in biotechnological production. By altering Escherichia coli bacteria with recombinant DNA methods or modifying one amino acid contained in pig-derived insulin, Eli Lilly and Novo Nordisk, respectively, could mass-produce insulin and eliminate smaller manufacturers. These methods enabled each company to produce biosynthetic “human” insulin—and market it as such, at a much higher price.