Last June, after 129,000 vials of Novo Nordisk’s long-acting insulin were stolen from a parked truck in North Carolina, the Food and Drug Administration warned diabetes patients not to take drugs with the stolen lot numbers. But it was too late. The vials turned up in a Texas medical center. Because the insulin had not been refrigerated, patients who used it developed unsafe blood-sugar levels. The authorities have recovered only 2 percent of the missing vials.

Vials of stolen or diverted drugs can also wind up in the hands of counterfeiters, who may relabel them or even replace their contents with cheaper ingredients. Such counterfeits also find their way into the legitimate supply. In 2002, Timothy Fagan, a 16-year-old on Long Island, experienced painful spasms after getting a diverted dose of Epogen to treat his anemia after a liver transplant. The drug had been relabeled, stored in the back of a strip club and ultimately resold to a national wholesaler and dispensed by a pharmacy.

In the wake of the Connecticut theft, Eli Lilly tried to reassure consumers by asserting that the American drug distribution system is “tightly controlled and monitored, making it extremely difficult for stolen product to make it to patients through legitimate channels.” Yet common sense tells us that you don’t steal a big volume of anything unless you know you can resell it.

Pharmaceuticals account for only 5 percent of all cargo thefts, according to FreightWatch International, a freight security company. This is far less than electronics, the most-stolen kind of cargo, which account for almost a fourth. But drugs are in first place in the category of value per incident. Last year, while the average electronics theft amounted to $814,000, the average pharmaceutical theft was worth $4 million. Since 2006, the number of drug thefts has quadrupled.

Consumers could be protected from this. Track-and-trace technology can put a unique code on each bottle, even each pill produced. Unfortunately, Eli Lilly’s psychiatric drugs left that Connecticut warehouse with neither. Drug companies are apparently reluctant to pay the nominal cost of tagging pills and bottles (only about 25 cents a bottle, after an initial investment of $1 million to $2 million). Unlike consumers, they are protected from theft by insurance. The F.D.A. should require that drug makers tag every bottle.