Fibromyalgia: Is insulin resistance ‘the missing link?’

Fibromyalgia is a chronic condition that causes abnormal pain all over the body, increased sensitivity to pain, and heightened feelings of fatigue, among other symptoms.

According to the Centers for Disease Control and Prevention (CDC), fibromyalgia affects 4 million people in the United States alone, which equates to about 2% of the population. However, researchers still have no idea what causes this widespread condition.

Recently though, researchers from The University of Texas Medical Branch in Galveston made an intriguing find.

In collaboration with colleagues from other institutions, the researchers identified a connection between fibromyalgia and insulin resistance. They were also able to treat fibromyalgia-related pain by using a drug that doctors commonly prescribe to help the body regulate blood sugar levels.

“Earlier studies discovered that insulin resistance causes dysfunction within the brain’s small blood vessels. Since this issue is also present in fibromyalgia, we investigated whether insulin resistance is the missing link in this disorder.”

First author Dr. Miguel Pappolla

“We showed that most — if not all — patients with fibromyalgia can be identified by their A1c levels, which reflects average blood sugar levels over the past 2 to 3 months,” Dr. Pappolla adds.

The A1c test is a blood test that allows doctors to measure a person’s blood sugar levels by looking at “hemoglobin A1c,” a blood cell protein that binds to the simple sugar glucose. Doctors use this test to diagnose prediabetes and type 2 diabetes.

For their study, the researchers recruited 23 people with fibromyalgia whose doctors had referred them to a specialist clinic for the treatment of muscular or connective tissue pain. They published their findings in the journal PLOS ONE.

When the investigators compared the A1c test results of the people with fibromyalgia with those of age-matched controls, they found that the former group had significantly higher levels of hemoglobin A1c than the latter, indicating a measure of insulin resistance.

“[People with prediabetes] with slightly elevated A1c values carry a higher risk of developing central (brain) pain, a hallmark of fibromyalgia and other chronic pain disorders,” notes Dr. Pappolla, pointing out that this link between insulin resistance and fibromyalgia has been around for a long time.

Surprisingly, it went unnoticed. “Considering the extensive research on fibromyalgia, we were puzzled that prior studies had overlooked this simple connection,” the first author says.

“The main reason for this oversight is that about half of fibromyalgia patients have A1c values currently considered within the normal range. However, this is the first study to analyze these levels normalized for the person’s age, as optimal A1c levels do vary throughout life,” the researcher continues.