Important Points:
- Fibromyalgia
- Chronic pain
- hemoglobin A1c
- insulin resistance
Is insulin resistance linked to chronic pain?
Yes, insulin resistance and chronic pain are linked. One study looked at 23 fibromyalgia patients. Their age-adjusted hemoglobin A1c, a measure of insulin resistance, ran significantly higher than in matched controls. Metformin reduced their pain.
An estimated 10 million adults in the United States live with fibromyalgia. It causes pain throughout the body, often to the point where it’s hard to function. Could insulin resistance be the key to understanding and treating fibromyalgia and other chronic pain? Here is some of what current research says.
So, what is Fibromyalgia?
Fibromyalgia brings chronic, widespread pain, more sensitivity to pain, and strong feelings of fatigue, brain fog, and more. It is still poorly understood. It is also hard to diagnose and hard to manage, and it lowers the quality of life for those who live with it. Reports put its global prevalence at an estimated 2.7%. Women outnumber men nearly three to one. In addition, a couple of studies have noted that fibromyalgia seems to be more common in people with Type 2 diabetes (T2D). That suggests a link between the two conditions that is worth more study. Experts agree that genes and environment play a part in fibromyalgia. But little is known about how and why it develops.
Doctors diagnose fibromyalgia using the American College of Rheumatology (ACR) guidelines. The Widespread Pain Index measures pain or tenderness felt in 19 different body regions in the week before the visit. The Severity Scale comes from the patient’s own rating of symptoms like fatigue and brain fog on a scale from 0 to 3. ACR guidelines combine these two measures on a scale from 0 to 31. By their standard, a score of 13 or higher means a diagnosis of fibromyalgia.
The global cost of FM is huge. In the United States alone, the healthcare cost is around $100 billion/year, similar to reports from European countries. Patients with FM also feel pain at lower levels. Because of that, they have more muscle, joint and spine problems with symptoms. Those problems add to the cost of managing this disorder.
Many theories try to explain its wide range of symptoms. They include inherited defects, problems in nerve signal pathways such as substance P, immune dysregulation (an immune system out of balance), and several others. Sadly, none of these ideas has led to real progress beyond treating symptoms. In fact, recent reviews of FM published in 2016 and 2017 concluded that there had been no real advances in our understanding of this disease.
2. What are the Similarities Between Fibromyalgia and Insulin Resistance?
Newer reviews of fibromyalgia research do not mention its suggested link to insulin resistance or diabetes. Even so, the two conditions affect brain vasculature (the brain’s blood vessels) in strikingly similar ways.
Miguel Pappolla, MD, PhD, is a professor of neurology at the University of Texas Medical Branch. He is also medical director of St. Michael’s Pain and Spine Clinics in Houston. He says insulin resistance is known to impair brain microcirculation (blood flow in tiny vessels). That leads to slowed blood flow and oxygen delivery (hypo-perfusion) in certain brain regions. “What is very interesting,” he said, “is that patients with fibromyalgia also have hypo-perfusion in several brain areas.” The question remains whether insulin resistance may be behind these similar drops in blood flow in people with fibromyalgia.
- Do people with fibromyalgia have higher A1c levels?
To look into this, Dr. Pappolla led a retrospective, cross-sectional study. The team reviewed medical records from 23 patients (21 females, 2 males; 11 White, 8 Hispanic, 4 African American; ages 35 to 60) at St. Michael’s Pain and Spine Clinics. All 23 patients met the ACR criteria for a fibromyalgia diagnosis.
To measure insulin resistance, the team chose the hemoglobin A1c. Values between 5.7 and 6.4 define prediabetes, and values of 6.5 or more mean diabetes. They compared the A1cs on record for the 23 patients with fibromyalgia to two separate control groups. One was the non-diabetic subset (1,350 people) from the Framingham Offspring Study with normal glucose tolerance (FOS NGT). The other was the non-diabetic subset (1,592 people) from the National Health and Nutrition Examination Survey (NHANES).
The team compared the A1c results of the people with fibromyalgia to controls of the same age. The people with fibromyalgia had significantly higher hemoglobin A1c levels. A1c is 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. He points out that this link between insulin resistance and fibromyalgia has been around for a long time. Surprisingly, no one noticed it. “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.
“Adjustment for the patients’ age was critical in highlighting the differences between patients and control subjects,” he explains.
As part of the study, the team gave metformin to people with fibromyalgia and muscle or connective tissue pain. Metformin is a drug people typically take to treat insulin resistance.
Metformin reduced pain in this cohort. That led the researchers to suggest this common drug could be a workable, cheaper treatment for some people with this chronic pain condition.
“In the [U.S.] alone, the healthcare cost is around $100 billion [per] year; comparable to reports in European countries,” the researchers write in the study paper.
“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. It lets doctors 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.
To back up this finding, the team also checked pain scores over time. They looked at FM patients whose insulin resistance had been treated with drugs. This subgroup reported dramatic drops in their myofascial pain (muscle pain) after taking metformin.
- Can metformin help fibromyalgia pain?
This evidence is early, but it suggests a disease link between Fibromyalgia and Insulin Resistance. That may lead to better treatment plans. Metformin, a drug commonly used to treat diabetes by targeting insulin resistance, has also shown promise for fibromyalgia pain. It may lead not only to a radical paradigm shift for the management of [fibromyalgia] but may also save billions of dollars to healthcare systems around the world.
That said, more research is needed. We need to better understand how insulin resistance links to fibromyalgia and other kinds of chronic pain.
Frequently asked questions
Is fibromyalgia more common in people with diabetes?
It appears to be. A couple of studies have found fibromyalgia more often in people with type 2 diabetes. That points to a link between the two conditions. Insulin resistance and fibromyalgia also affect the brain’s blood vessels in strikingly similar ways. Both slow blood flow and oxygen delivery in several brain regions.
How is fibromyalgia diagnosed?
Doctors use American College of Rheumatology criteria. The Widespread Pain Index counts pain or tenderness in 19 body regions over the past week. The Severity Scale rates symptoms such as fatigue and brain fog from 0 to 3. The two combine into a score from 0 to 31. A score of 13 or higher corresponds to fibromyalgia.
Why was the link between insulin resistance and fibromyalgia missed?
About half of fibromyalgia patients have A1c values inside today’s normal range. So the pattern hid in plain sight. The Pappolla study was the first to adjust A1c for each patient’s age, because the best A1c levels change over a lifetime. Once the results were adjusted for age, the gap between patients and controls became clear.
What does an A1c test measure?
The A1c test reflects your average blood sugar over the past two to three months. It measures hemoglobin A1c, a blood protein that binds glucose. Doctors use it to diagnose prediabetes and type 2 diabetes. Values between 5.7 and 6.4 define prediabetes. A value of 6.5 or higher means diabetes.
How common is fibromyalgia?
An estimated 10 million adults in the United States live with fibromyalgia. It causes pain throughout the body, often to the point where it is hard to function. The estimated global prevalence is 2.7 percent. Women outnumber men nearly three to one.
Related reading
References
- NCBI (2016): A Correlative Relationship Between Chronic Pain and Insulin Resistance in Zucker Fatty Rats: Role of Downregulation of Insulin Receptors. Retrieved from
https://www.ncbi.nlm.nih.gov/pubmed/26705975
- Science Daily (2019): Does insulin resistance cause fibromyalgia? Retrieved from
https://www.sciencedaily.com/releases/2019/05/190507145523.htm
- MedicalNewsToday (2019): Fibromyalgia: Is insulin resistance ‘the missing link?’ Retrieved from
https://www.medicalnewstoday.com/articles/325155.php#1
- Plos One (2019): Is insulin resistance the cause of fibromyalgia? A preliminary report. Retrieved from
https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0216079
- Practical Pain Management (2019): Fibromyalgia and Insulin Resistance: Correlational or Causal Relationship? Retrieved from
- Healthline (2019): Drug Used to Treat Diabetes May Be Effective Against Fibromyalgia. Retrieved from
https://www.healthline.com/health-news/does-insulin-resistance-cause-fibromyalgia
Medically reviewed by Dr. Gurpreet Singh Padda, MD, MBA, MHP
Interventional pain physician, addiction medicine specialist and obesity medicine diplomate.
Licensed in Missouri and Illinois.
Last reviewed June 18, 2026
