Fasting insulin test · Chronic pain

Fasting Insulin Test: What a Normal A1c Can Hide When You Hurt

A normal A1c can hide years of rising insulin. A fasting insulin test shows the extra insulin the body is making to keep glucose in range, and that excess injures blood vessels and makes nerves quicker to fire, which is why it belongs in a chronic pain workup.

Your A1c came back fine and your back still hurts. The number that connects the two is usually the one nobody ordered.

A fasting insulin test measures how hard the pancreas is working to hold blood sugar steady, and it can show metabolic strain years before glucose moves. Most people who have lived with chronic pain for years have never had one drawn.

The video The Cost of Pain Is Paid in Years, from The Pained Brain by Dr. Gurpreet Singh Padda, MD, MBA, MHP, and Dr. KrisJay Fucanan, MD, argues that long-lasting pain often lives inside a body running on high insulin. The practical question for you is what would show that in your own numbers, what a routine visit checks, and what it leaves unmeasured.

Why don’t doctors order a fasting insulin test?

A standard visit usually looks at fasting glucose, sometimes hemoglobin A1c, blood pressure, weight and cholesterol. Those are useful numbers. They are also late numbers. Insulin is the hormone that moves sugar out of the blood and into cells. When cells start ignoring it, the pancreas simply makes more, and glucose stays inside its normal range for years while insulin keeps rising. A normal A1c tells you the system is still coping. It does not tell you what the coping is taking.

That hidden phase is not rare. Among American adults without diabetes, high fasting insulin reached 41.4 percent in 2017-2018, up from 28.2 percent in 1999-2000, while measurable insulin resistance reached 38.4 percent, up from 24.8 percent. In that national survey work, high fasting insulin meant a level above 10 µU/mL. That is a population cut point, not a diagnosis. The earlier stages are laid out in what insulin resistance looks like before diabetes.

Dr. Padda has said he spent years telling patients with prediabetes that their A1c was not too bad. The physiology changed his mind. By the time glucose finally rises, the pancreas has been straining for a long while, and blood vessels and nerves have been soaking in the extra insulin the entire time.

Is chronic pain linked to insulin resistance?

In the latest national survey, 24.3 percent of American adults had pain on most days. It is far more common where metabolic disease already sits, at 37.7 percent of adults with diabetes and 40.7 percent of adults with coronary heart disease. The overlap has a biological basis. Excess insulin injures the inner lining of blood vessels, cuts the blood supply that nerves depend on, and makes a nerve quicker to fire. A second driver is visceral fat, the fat packed around the organs, which acts less like storage and more like a gland releasing inflammatory signals around the clock.

The traffic runs in both directions. In 84,565 British adults over sixty with no diabetes at the start, pain at four to seven body sites raised the hazard of later type 2 diabetes to 1.198, and weight gain accounted for close to half of that. Hurting limits movement, less movement adds fat, fat drives insulin up, and insulin sharpens the pain. That loop is the reason chronic pain and metabolic health are worth measuring side by side.

Biology is not the only engine. Among Americans without a four-year degree, pain at age 52 was reported by 40 percent of the 1965 birth cohort compared with 32 percent of the 1955 cohort, and body mass explained only about a quarter of that rise. Schooling and work shape who hurts, and the food, sleep and movement that push insulin up.

Does a normal CRP mean there is no inflammation?

The blood marker most often ordered to look for inflammation is C-reactive protein, or CRP. A normal result is easy to read as a quiet body, and the research does not back that reading. In 5,905 American adults scored for visceral fat, the top quarter carried 1.87 times the odds of chronic pain seen in the bottom quarter, and CRP accounted for only 7.4 percent of that association. Studies using inherited gene variants find no causal effect of higher CRP on spinal pain.

What seems to matter is inflammation that switches on and never switches off, which the book calls metaflammation. In 98 people with new low back pain, those who recovered showed a large immune response that rose and then settled, while those whose pain turned chronic showed no such wave. One marker on one morning cannot capture that, so the useful move is to measure the terrain that keeps it smoldering.

Can you be insulin resistant at a normal weight?

Weight and body mass index miss the same problem from a different angle. In a nine-year study of 3,546 Chinese adults with an average BMI of 23.76, squarely normal, each unit rise in a bedside insulin-resistance index built from fasting triglycerides and glucose raised the odds of new severe chronic pain 1.51-fold. East Asian and South Asian adults often carry more fat in the liver and around the organs at the same BMI, the pattern known as skinny fat: thin outside, insulin resistant inside.

That is where bioimpedance body composition earns its place. It estimates how much of your weight is fat and how much is lean tissue, which a bathroom scale cannot separate. It is not a diagnosis; it shows a compartment total weight conceals, which is why body composition is not the same as weight.

What Measura adds to a standard panel

Measura [Cardiometabolic and Autonomic Health Analysis] collects measurements and sends every result to your physician, who decides what they mean; the service neither treats nor diagnoses by itself. For someone whose pain has been handled one joint at a time, three measurements speak directly to the terrain described above.

• Laboratory panels. Blood work that can add fasting insulin to glucose and A1c, along with the triglyceride and HDL pattern that feeds the insulin-resistance index.
• Body composition. Fat and lean tissue as separate numbers, so a normal weight cannot hide a high fat share.
• Arterial stiffness and endothelial function. How flexible the arteries are and how well the vessel lining responds, the same lining that excess insulin damages.

None of these explains why a particular joint hurts. Together they describe the body the pain is living in, the part no scan of the joint can show. See how to read your Measura report.

What to ask for at your next visit

The next step is small and specific. Ask for the fasting insulin number itself, not only the glucose. Ask whether a triglyceride-glucose index can be calculated from labs you already have; it needs just fasting triglycerides and fasting glucose. Ask to have your waist measured in centimeters, since the metabolic-health definition sets it below 102 cm for men and 88 cm for women. And ask that the number of places you hurt be written into your chart.

By every criterion at once, fewer than 12.2 percent of US adults counted as metabolically healthy in NHANES 2009–2016 data; judged by the stricter post-2021 yardstick, the share falls below 7 percent. In Dr. Padda’s practice, fewer than 1 percent of chronic pain patients meet that definition; these are practice-reported figures from our own population, not trial outcomes, and individual results vary. Unmeasured is unmanaged. Nothing here is a reason to change a medication, so bring the numbers to your physician. The studies behind every figure are in the Chapter 1 supplement, and the next piece of the argument is what losing feeling in the feet tells you.

Frequently asked questions

References

• Wu, C., Ke, Y., & Nianogo, R. A. (2025). Trends in Hyperinsulinemia and Insulin Resistance Among Nondiabetic US Adults, NHANES, 1999-2018. Journal of Clinical Medicine, 14(9), Article 3215. https://doi.org/10.3390/jcm14093215
• Zhu, J., Wang, Y., Yu, G., Li, L., He, J., Liao, H., & Wu, X. (2025). Association between metabolic score for visceral fat and chronic pain: a cross-sectional analysis of NHANES 1999-2004. Frontiers in Nutrition, 12, Article 1545774. https://doi.org/10.3389/fnut.2025.1545774
• Zhao, D., Cui, Y., Lu, H., Yang, H., Guo, W., Shan, Z., & Wu, C. (2026). Association Between the Triglyceride-Glucose Index and Incident Chronic Severe Pain in Middle-Aged and Older Chinese Adults: A Nationwide Cohort Study. Pain Research & Management, 2026, 2464060. https://doi.org/10.1155/prm/2464060
• Liang, J., He, X., Ouyang, Y., Song, X., Li, M., Qi, T., Chen, J., Zhang, X., Guo, X., Jia, T., Wu, S., Kou, C., & Bai, W. (2026). Association between chronic pain and type 2 diabetes in older adults: A prospective study in the UK Biobank. The Journal of Pain, 43, 106272. https://doi.org/10.1016/j.jpain.2026.106272
• Rikard, S. M., Strahan, A. E., Schmit, K. M., & Guy, G. P. (2023). Chronic Pain Among Adults – United States, 2019-2021. MMWR. Morbidity and Mortality Weekly Report, 72(15), 379–385. https://doi.org/10.15585/mmwr.mm7215a1
• Suri, P., Tsepilov, Y. A., Elgaeva, E. E., Williams, F. M. K., Freidin, M. B., & Stanaway, I. B. (2025). A Mendelian randomization study finds no evidence for causal effects of C-reactive protein on chronic pain conditions. Pain medicine (Malden, Mass.), 26(4), 222–224. https://doi.org/10.1093/pm/pnae122
• Case, A., Deaton, A., & Stone, A. A. (2020). Decoding the mystery of American pain reveals a warning for the future. Proceedings of the National Academy of Sciences of the United States of America, 117(40), 24785-24789. https://doi.org/10.1073/pnas.2012350117
• Araújo, J., Cai, J., & Stevens, J. (2019). Prevalence of Optimal Metabolic Health in American Adults: National Health and Nutrition Examination Survey 2009-2016. Metabolic Syndrome and Related Disorders, 17(1), 46–52. https://doi.org/10.1089/met.2018.0105

Related reading

• Monofilament Test: What It Means When You Can’t Feel Your Feet
• Laboratory Panels

Medically reviewed by Dr. Gurpreet Singh Padda, MD, MBA, MHP, medical director of Measura. Last reviewed September 12, 2026.