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Researchers say insulin resistance may be linked to fibromyalgia. Getty Images

Could the key to understanding and treating fibromyalgia involve insulin resistance?

An estimated 10 million adults in the United States live with fibromyalgia — a condition that causes pain throughout the body, sometimes to the point where it’s difficult to function.

It can be a tricky condition to diagnose and treat, but researchers from the University of Texas Medical Branch (UTMB) at Galveston found that metformin, a drug intended to combat insulin resistance in people with diabetes, was effective at reducing pain in people with fibromyalgia.

They published their findings earlier this month in the medical journal PLOS ONE.

The data is preliminary and more research is needed.

However, the research is already helping shine new light on what causes fibromyalgia, along with how it can be managed.

Once treated with the insulin resistance-targeting drug, fibromyalgia patients in the study saw pain levels go down dramatically.

But getting to that point of diagnosis is a story in itself.

“The hard thing is that fibromyalgia is still based on a diagnosis of exclusion, so you have to rule out other neuropathies before you can say someone has fibromyalgia,” Dr. Edward Rubin, pain management specialist at Long Island Jewish Medical Center in New York, told Healthline.

“Is it true diabetic neuropathy, or could it come from the lower back?” he noted. “There are a lot of different issues that you would have to rule out before you call it fibromyalgia. It’s not like there’s an MRI or a lab test that definitively diagnoses it.”

To that end, the UTMB researchers needed to develop two groups to study: one with fibromyalgia and one without.

Dr. Miguel Pappolla, UTMB professor of neurology and a study author, told Healthline that, for the first time, his research team used a common blood test to identify patients with fibromyalgia.

“In the observation of my own fibromyalgia patients, there’s a very high prevalence of borderline, or slightly elevated, hemoglobin A1c,” he explained.

While a possible connection between elevated A1C levels (a marker of blood sugar in the body) and fibromyalgia had been suggested in the past, the premise had been mostly rejected because many people with fibromyalgia had A1C levels that were considered normal.

“However, those values considered currently normal may not be so, because when you adjust for age the values are not quite normal when you compare with groups of other patients at the same age group,” said Pappolla. “In clinical practice, most doctors don’t do the age adjustment.”

Once the researchers adjusted for age, it was found that the vast majority of patients with fibromyalgia studied had elevated A1C levels.

“Within all the neuropathic issues we see in diabetic patients with peripheral neuropathy and other pain syndromes we see with diabetes, it definitely makes sense that this diffuse neuropathic pain that fibromyalgia patients experience could have some underlying connection to poor sugar control,” said Rubin.

Pappolla said that while many of his group’s findings were expected on some level, he did not expect patients to see such dramatic reductions in their pain levels.

Given the high cost of treating fibromyalgia in the United States, the research — preliminary though it may be — could eventually be a game changer.

“If we are right — and we don’t know for sure because this is preliminary — just with fibromyalgia alone, there’s a huge impact on the healthcare budget,” said Pappolla. “It’s estimated to cost the American healthcare budget $100 billion a year. We’re talking about something that’s comparable to Alzheimer’s. It’s not a small amount.”

Some of this $100 billion total comes down to people getting expensive, and ultimately unhelpful, treatments for a condition that still isn’t well understood.

“When a fibromyalgia patient goes to a regular doctor that is not familiar with these concepts, they might be operated on or given a high dose of opiates,” said Pappolla. “Thirty to 40 percent of fibromyalgia patients have surgery for a dominant pain site, like lumbar spine or a joint, and they respond poorly to surgery. This drives costs.”

Researchers also think that diagnosing and treating the condition early might be key in stopping its progress.

“There are papers suggesting that the earlier you treat prediabetes, you’ll be in a window of opportunity to reverse the peripheral neuropathy,” explained Pappolla. “We may be seeing the same phenomenon here with patients with fibromyalgia. If we treat them early, we may be able to arrest the disease or even reverse it.”

UTMB researchers have made some promising strides in the understanding and treatment of fibromyalgia. But there’s still lots of work to be done.

Pappolla says that his team will need to confirm their findings with other markers of insulin resistance. Some of these markers are complex and some may need to be adjusted for age.

A second step involves finding more study participants.

“The problem that we have is that we don’t have controlled populations now, and developing these controlled populations is very expensive,” said Pappolla. “You need hundreds, perhaps thousands, of patients of different ages, and we’ll be seeking National Institutes of Health (NIH) funding to advance this research.”

Pappolla says future research will explore not just fibromyalgia, but other areas of chronic pain as well. To do this, UTMB researchers would like to start building a database of patients.

There’s a wealth of data still waiting to be discovered, but the results of this round of research are still significant.

“It’s a low-cost medication, easy to administer,” said Rubin. “It would be off-label as usage, but there are lots of off-label usages for medications where they’ve been used for different purposes. We’ve seen it with ketamine for depression. We’ve seen it with aspirin for heart conditions. There’s a long history of meds out there that have been repurposed and this is another interesting example.”

Metformin, a drug commonly used to treat diabetes patients by targeting insulin resistance, has shown promise with treating pain from fibromyalgia.

Researchers also found that a simple blood test is effective at diagnosing fibromyalgia — a significant step given that it’s traditionally been a difficult condition to diagnose.

More research is needed to better understand the link between insulin resistance and fibromyalgia, along with other types of chronic pain.