In the United States, said Dr. Zonszein at Montefiore, the price of Humalog, Lilly’s analogue insulin, was typically two to four times that of its older human insulin line, called Humulin. “There is not a lot of difference between Humulin and analogues,” he said, but he noted that Humulin was getting “hard to find.” Sanofi Aventis has stopped selling its older product in the United States, and Mr. Kliff, the financial analyst, said other companies were likely to follow suit, effectively forcing patients to use the costlier versions.

Dr. Todd Hobbs, chief medical officer of Novo Nordisk, defended the rising prices of insulin, linking them to medical benefits. “The cost to develop these new insulin products has been enormous, and the cost of the insulin to the consumer in developed countries has risen to enable these and future advancements to occur,” he wrote in an email.

Patients get squeezed between insurers or employers, who are trying to limit their outlays, and the suppliers. The constant shifts in products and prices are a challenge for even the most sophisticated consumers.

Denise Lombard, an insurance broker in Oakland, Calif., whose 16-year-old daughter, Gabrielle Woodland, has diabetes, said many policies contained “not one word about how they are going to cover insulin and supplies.” Gabrielle’s current policy does not cover glucagon, a hormone injection — which retails at $272.72 a dose — that families of diabetic children are told to stock should they faint because their blood sugar drops too low.

Image The insulin pumps Gabrielle Woodland and others use for Type 1 diabetes are efficient, but expensive. Credit... Nathan Weyland for The New York Times

Jonathan Lloyd, a pharmacist in upstate New York, has been frustrated trying to manage the care of his daughter, Erin, 25, who uses a pump with a built-in glucose meter and is teaching in Nicaragua. When Mr. Lloyd went to fill the four prescriptions for her supplies this year, he discovered many of them were no longer covered by his insurer, which had switched to reimburse a different brand of insulin and a different metering system, because the insurer got a better deal.

He now faces a dilemma: His daughter could switch to the new type of meter, which cannot communicate with her pump, which would mean her current meter would sit uselessly on her waist. Or he can pay thousands of dollars to buy supplies for the meter she already has. “It’s so complicated — there are all these hidden costs, and I’m a pharmacist, for crying out loud,” he said.