Human vs. Beef/Pork Insulin
The following is
an adaptation of a position statement
that originally appeared in the June
1995 edition of Canadian Diabetes, a
publication of the Canadian Diabetes
Association's Clinical & Scientific
Section. The findings of the
"Quebec Committee" that
studied the questions surrounding the
discontinuation of a brand of beef/pork
insulin are presented below. Your
questions and comments are welcome.
What place does
beef/pork insulin have in treating diabetes?
And what happens when people switch from
animal to human insulins?
Those were two of the questions
raised in early 1995, when Novo Nordisk
Canada Inc. decided to stop producing
beef/pork insulin, effective June 30,
l995. The only other Canadian company
making beef/pork insulin, Eli Lilly
Canada Inc., announced it would continue
to do so, at least until 1999.
The Association of
Endocrinologists of Quebec, in
cooperation with the Order of
Pharmacists of Quebec, responded to this
news by forming an ad hoc committee. Its
role: to evaluate the place of beef/pork
insulin, and to make recommendations for
the best ways of transferring from one
type of insulin to another.
One quarter use animal insulin
According to estimates provided
by the insulin-making companies, about
24 percent of diabetes patients across
Canada use animal insulins. That ranges
from 18 percent in Quebec to 30 percent
in New Brunswick/Prince Edward Island.
In the way their molecules are
structured, human insulin differs from
pork insulin by a single amino acid, and
from beef insulin by three amino acids.
What does that mean? For one, it means
that human insulin dissolves in water
more easily than pork insulin and gives
rise to less antibodies than beef
insulin. Here are some other ways the
properties of each type of insulin
influence how they're handled in the
insulin is absorbed quickly, and
is active for a shorter period.
presence of insulin antibodies
could slow the action of animal
insulins, especially beef.
Since highly purified animal
and human insulins have come on the
market, certain problems have all but
disappeared (such as allergies, the loss
of fatty tissue where injections occur,
and resistance to the effects of
insulin). Less than five percent of
people who use insulin suffer these
Pros and cons
Overall, changing to human
insulin means little difference in
controlling diabetes, though some
patients who have poor control using
animal insulin may benefit.
Switching from animal to human
insulin often means only small changes
in the dosage. About 15 percent of the
people who switch, however, may require
significant dosage adjustments.
Compared to animal insulin,
human NPH insulin (an
intermediate-acting insulin preparation)
has a shorter action period. Therefore,
patients who had required just a single
morning injection using animal insulin
may need a second NPH injection later in
Patients who were previously on
NPH twice a day may also have to shift
their injection from supper to bedtime.
This avoids low blood sugar at night and
high blood sugar in the morning.
For the same reason, injections
of long-acting forms of human insulin
(Ultralente) may have to move from the
morning to the evening.
One advantage of human insulin
over animal insulin is its availability
in cartridges for use in pen injectors.
That simplifies treatment for people who
must have several injections, and may be
much easier for older patients or those
with sight problems.
The main complication of
insulin treatment is low blood sugar
(hypoglycemia). Recognizing the signs
early is the best defense against any
impact on the nervous system or comas.
Some 30 percent of patients on insulin
will have at least one hypoglycemic coma
in their lifetime, and three percent
will have recurring comas. As well, 10
percent will have a severe hypoglycemic
reaction each year.
Does low blood sugar increase
after switching to human insulin? That
controversy hasn't been resolved. Most
studies don't show any difference in the
frequency, impact, or awareness of low
blood sugar between people on animal and
human insulin. Any reported differences
are small, and their meaning is
questionable. The introduction of human
insulin also hasn't increased the
incidence of sudden death in people with
diabetes under age 50.
Overall, then, there doesn't
seem to be a case that low blood sugar
is any worse for patients on human
insulin. Anecdotes and observations from
doctors show that on animal insulin some
patients, better controlled, can
recognize on their low blood sugar more
easily, or feel more confident about
their treatment. It is recommended by
some that more studies are needed on
this subject and that animal insulins
should remain available until further
studies are completed.
The bottom line:
After reviewing the evidence,
the ad hoc committee came up with a list
of recommendations and a protocol for
switching insulins, which the
Association du Diabete du Quebec and the
Canadian Diabetes Association's Clinical
& Scientific Section endorsed.
The key recommendations
can control their diabetes well with
beef/pork insulin should continue on
it. Sometimes, switching to human
insulin means increased injections.
If patients are under control with
beef/pork insulin and don't want
more injections, that's another
reason for staying with animal
believe they can feel low blood
sugar better on animal insulin can
try returning to it.
percentage of patients on animal
insulin who have the problems
mentioned earlier (allergies, losing
fatty tissue at injection sites,
resistance to insulin's effects)
should switch to human insulin.
In cases where
insulin is needed only
intermittently, human insulin is
Who can decide
on changing the type of insulin?
That should be left to the
endocrinologist or the treating
physician. Except in
emergencies, pharmacists are not
authorized to exchange human
insulins for beef/pork insulins.
Unless their reasons are justified,
medical professionals also shouldn't
pressure patients to switch from
animal to human insulins.
With that in mind, the ad hoc
committee suggested that when switching
transfers should be medically
must receive detailed
information about how the change
effectively adjust the doses of
insulin, patients must
temporarily do more self blood
sugar testing more often. If
not, closer medical follow-up is
who were previously on animal
insulin should lower the initial
dose of human insulin by 10 to
can use the same dosage schedule
if switching from Novo Nordisk's
animal insulin to Eli Lilly's
animal brand of insulin.
Adapted from the
Report of the Ad Hoc Committee on
Beef-Pork Insulins by Nahla Aris-Jilwan
MD, Pierre Malheux MD, Tina Kader MD,
Alain Boisvert B.Pharm, DPH, MSc, and
Sara Meltzer MD. Adapted by Stuart
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