Some Canadians with diabetes are calling on the federal government to guarantee supplies of animal-based insulin, saying they face potentially fatal consequences if they can't get it.

Earlier this month, the pharmaceutical company Eli Lilly announced it's pulling four types of insulin off the Canadian market, including the last animal-based form of the hormone.

The company said sales of the pork-based insulin were slow.

As many as 700 people use animal insulin in Canada, said Colleen Fuller of the Society for Diabetic Rights.

"I nearly died I don't know how many times," said Fuller, describing her reaction to the synthetic form of the drug. "I couldn't control my blood sugars."

"I could be standing here, just like this, and the next second I would be on the floor and unconscious."

Colleen Fuller

Synthetic insulin works in the majority of diabetics, but some people, like Fuller, have reported having serious medical problems with the synthetics, including comas, seizures, convulsions and hypoglycemia.

The group is worried people may not be able to tolerate synthetic insulin and there may not be enough time to find a suitable replacement.

Fuller's group and the Insulin Dependent Diabetes Trust are calling on Health Canada to guarantee current insulin supplies, including Eli Lilly's animal-based form.

"Insulin is a very personal thing in each individual," said Dr. John Hunt of Vancouver, who said he's tested every kind of insulin in patients and supports the groups' efforts. "One insulin will suit one person. And another insulin will produce real problems in the next person."

Health Canada said it cannot force a manufacturer to make a certain drug. The department is working with other drug companies to keep a steady supply of animal-based insulin.

A British company has applied to Canadian regulators to sell its animal-based insulin, but there's no guarantee approval will be granted or come in time to prevent a gap in supply.

Eli Lilly will stop selling animal-based insulin in Canada in April.