Are You Allergic to Insulin or Insulin Resistant?

The terms are so similar that it's easy to confuse being allergic to insulin with insulin resistance. But these days, an allergy to insulin is exceedingly uncommon.

"It is extremely rare," says Shahla Nader-Eftekhari, MD, professor of internal medicine at The University of Texas Health Science Center at Houston (UT Health.) "If you were allergic to insulin, you'd have local effects at the site or generalized effects, but because we have synthetic insulin, it's very rare."

Years ago, she explains, beef or pork insulin was used and then it was more common to have an allergy to insulin. Why would a diabetic be allergic to the very medicine that's needed to keep him alive? "Years ago, animal sources of insulin produced antibodies in some patients and these patients became resistant to the insulin because of the antibody reaction," explains Carlos R. Hamilton, Jr. MD, of the University of Texas Health Science Center at Houston (UTHealth). "But that's not really a problem today."

What is a huge problem, however, is insulin resistance. In this condition, also called metabolic syndrome, a person makes insulin, but it does not lower the blood sugar as much as it should, Hamilton says. It's almost as if the pancreas gets stressed out and just can no longer keep up with the demand for insulin.

"The body reacts to that by putting out a higher amount of insulin into the bloodstream," he says. "Having excessive amounts of insulin in your blood causes your body to develop a whole sequence of problems."

Years ago, Nader-Eftekhari explains, if a person required more than 200 units of insulin per day, they were said to have insulin resistance. "But now, the term is used for people whose pancreas simply could not keep up with the demand for insulin," she says.

Individuals with insulin resistance tend to be obese,  Hamilton says. In addition, people with insulin resistance tend to have high blood pressure, high cholesterol, and high triglycerides, Hamilton says. They are more prone to heart attacks, and women with the syndrome also have a condition called polycystic ovarian syndrome, which can cause problems with fertility.

Some research shows that when obese women do get pregnant, their babies are at risk for developing metabolic problems during the prenatal period. The babies of obese moms also run a higher risk of becoming obese and getting type 2 diabetes later in life.

The good news? "You can effectively treat insulin resistance," Hamilton says. The best, most effective treatment of all is diet and weight loss, yet for many people, losing weight and keeping it off is very difficult. Additionally, there are medications to help with insulin resistance.

"Insulin resistance begins in utero for babies of obese moms." 30 May 2009. American Diabetes Association.