Short-Acting Insulin Time Not Short for Everyone

For most obese people with type 2 diabetes, short-acting
insulin may not be short-acting, say researchers.

People with type 2 diabetes may need insulin injections to help control the
spike in blood sugar that follows a meal.

Regular insulin takes about 45 minutes to work its way into the system --
with the dosage adjusted to the type and amount of food to be eaten, says
Jean-Luc Ardilouze, MD, PhD, professor of medicine at University of Sherbrooke
in Quebec, Canada.

"Of course, how many of us know exactly what, and how much, we are going
to eat 45 minutes before a meal? So the big advantage of short-acting insulin
was you could inject it immediately before eating," Ardilouze tells
WebMD.

Humalog and NovoLog are two examples of short-acting insulins.

Obesity and Short-Acting Insulin

Ardilouze became interested in the biology of fat tissue. He soon learned
that fat tissue has highly restricted blood flow -- and wondered what that
meant for obese people who take insulin injections.

When they studied short-acting insulin products, Ardilouze and colleagues
discovered that the bigger the dose, the longer the products took to work. They
reported the findings at the American Diabetes Association's 67th Annual
Scientific Sessions, held June 22-26 in Chicago.

"If you inject 10 units of short-acting insulin into obese subjects,
there is not much difference in time to peak effect," he says. "But the
time is tripled with triple the dose -- the kind of dose an obese person with
diabetes is much more likely to need."

This means that for obese people, short-acting insulin isn't short-acting.
Ardilouze says it may take as long as 45 minutes to work -- a fact that doctors
and patients don't know.

How could this be? After all, short-acting insulin products are marketed,
and priced, on the basis of their convenience. Ardilouze says he was amazed to
learn that short-acting insulin was approved by U.S. and Canadian authorities
without having been tested in obese people with type 2 diabetes.

"The big surprise when we started this study was to find out that the
[biochemical action] of short-acting insulin had been established in young,
lean, type 1 diabetics," Ardilouze says. "One product, in the tiny
writing on the label, there is one little part that says [it] was never studied
in obese people with type 2 diabetes."

That's true, says M. Sue Kirkman, MD, vice president for clinical affairs at
the American Diabetes Association.

"The initial trials looking at short-acting insulin were done in normal
individuals -- and all of the [biochemical action] studies are done in normal
people -- probably lean normal people," Kirkman tells WebMD. "Most
studies of rapid-acting insulins are done in type 1 diabetes, although I think
there are some type 2 studies, especially with the more recent
products."

Getting Good Blood Sugar Control

It's a problem, says ADA President Larry C. Deeb, MD, medical director of
the diabetes center at Tallahassee Memorial Hospital and a professor at both
the University of Florida and Florida State University.

"I feel very strongly about the issue of testing treatments in the kinds
of people who actually are going to get treated," Deeb tells WebMD.
"Every human isn't the same. Children aren't the same as adults, and obese
people aren't the same as the lean adults you routinely recruit for these
studies."

So what should obese patients do when they need insulin? Deeb agrees with
Ardilouze.

"You may need to take it earlier," he says. "You aren't going to
get rapid action for the obese patient. So you may need to rethink how you do
it."

Kirkman says that if patients are worried, they should test how well their
short-acting insulin is working.

"And if someone were really concerned, they could just take the insulin,
eat the meal, and test their blood glucose in two to thre hours," she
says.

Neither Kirkman nor Deeb was involved in the Ardilouze study. Ardilouze say
he will next study blood sugar control in obese patients taking short-acting
insulin for type 2 diabetes.

By Daniel DeNoon
Reviewed by Louise Chang
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