Insulin resistance explained: what it is, who is at risk, the blood sugar tests and their ranges, what the Diabetes Prevention Program showed, and the medicines that may be discussed.
Fact-checked against FDA labels and official sources; not yet reviewed by a licensed clinician. This page is education, not medical advice. Talk to your doctor before starting, stopping or changing any treatment.
Key facts
- Who to ask
- Endocrinology, Obesity medicine, Primary care, Registered dietitian
- Also called
- insulin resistant, prediabetes, pre-diabetes, borderline diabetes, insulin resistance syndrome
Key takeaways
- Insulin resistance means muscle, fat and liver cells respond poorly to insulin; it usually causes no symptoms.[1]
- Prediabetes ranges: A1C 5.7% to 6.4%, fasting glucose 100 to 125 mg/dL, or 140 to 199 mg/dL two hours into an OGTT.[1]
- In the Diabetes Prevention Program, a lifestyle program aiming for 7% weight loss cut new type 2 diabetes by 58%; metformin cut it by 31%.[3]
- About 115.2 million U.S. adults had prediabetes in 2023.[2]
- No medicine is FDA approved for insulin resistance itself; weight-management and diabetes medicines are prescribed for their labeled uses.[8]
In short: Insulin resistance means the cells in your muscles, fat and liver do not respond to insulin the way they should, so the body has to make more insulin to keep blood sugar in range. It usually causes no symptoms, it is closely linked to excess weight and inactivity, and it can lead to prediabetes and type 2 diabetes. The good news is that it responds well to change: in the landmark Diabetes Prevention Program, a lifestyle program aimed at 7% weight loss cut the rate of new type 2 diabetes by 58%. A clinician can check your blood sugar with simple tests and talk through options with you.
This page is general education to help you prepare for a conversation with a licensed clinician. It cannot tell you whether you have insulin resistance, and it is not a substitute for being examined and tested. Please research, ask questions and get evaluated before starting any treatment.
Insulin resistance and prediabetes in the U.S.
- 115.2 millionU.S. adults with prediabetes in 2023CDC National Diabetes Statistics Report
- 52.1%of adults 65 and older had prediabetes (31.3 million)CDC National Diabetes Statistics Report
- 58%fewer new cases of type 2 diabetes with the DPP lifestyle program vs placeboDiabetes Prevention Program, NEJM 2002
Checked on October 6, 2026
What insulin resistance is
Insulin is a hormone made by the pancreas. After you eat, it helps glucose (sugar) move from your blood into your cells, where it is used for energy or stored. The National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) describes insulin resistance as a condition in which your body does not respond to insulin the way it should: cells in the muscles, fat and liver do not take up glucose easily. To compensate, the pancreas makes more insulin. For a while that extra effort keeps blood sugar normal. Over time, the pancreas may not keep up, blood sugar rises, and prediabetes or type 2 diabetes can follow.
The NIDDK notes that researchers still do not fully understand what causes insulin resistance. It is not a moral failing and it is not simply about “eating too much sugar”. Genes, age, body fat (especially around the waist), physical activity, sleep and certain medicines all play a part.
Insulin resistance, prediabetes and type 2 diabetes: how they connect
These three terms describe stages along one path. Insulin resistance is the underlying problem. Prediabetes means blood sugar is higher than normal but not high enough to be called diabetes. Type 2 diabetes means blood sugar has crossed the diagnostic line, usually because insulin resistance is combined with the pancreas no longer making enough insulin. Not everyone with insulin resistance develops diabetes, and the path can often be slowed or stopped.
Who is more likely to have it
The NIDDK lists these risk factors for insulin resistance and prediabetes:
- overweight or obesity, or a large waist size;
- age 35 or older;
- a parent or sibling with diabetes;
- being African American, American Indian, Asian American, Hispanic or Latino, or Pacific Islander;
- not being physically active;
- smoking or exposure to secondhand smoke;
- a history of gestational diabetes or of giving birth to a baby weighing more than 9 pounds;
- certain conditions, including polycystic ovary syndrome (PCOS), Cushing’s syndrome and sleep apnea;
- some medicines, including glucocorticoids (steroids), some antipsychotics and some HIV medicines.
Having one or more of these does not mean you have insulin resistance. It means testing may be worth discussing with your clinician. Never stop a prescribed medicine because it appears on a list like this; ask the prescriber about alternatives instead.
Signs: often none at all
According to the NIDDK, people with insulin resistance and prediabetes usually have no symptoms. That is why so many people do not know they have it. One visible sign some people notice is acanthosis nigricans: MedlinePlus describes it as darker, thick, velvety skin in body folds and creases, typically on the neck, armpits and groin, and says it is frequently related to insulin resistance, diabetes and obesity. It often fades once the underlying cause is treated. Darker skin patches can have other causes, so a clinician should look at them.
Once blood sugar is high enough to be diabetes, the NIDDK lists symptoms such as increased urination, feeling very thirsty, feeling very hungry even after eating, blurred vision, fatigue, sores that do not heal and frequent infections. If you notice these, see a clinician promptly rather than waiting.
Tests a clinician may order
There is no single routine blood test labeled “insulin resistance” in everyday care. In practice, clinicians look at blood sugar, because that is what insulin resistance eventually affects. The NIDDK lists three standard tests and the ranges that indicate prediabetes:
| Item | Low | High |
|---|---|---|
| Fasting plasma glucose (mg/dL) | 100 | 125 |
| Oral glucose tolerance test, 2 hours (mg/dL) | 140 | 199 |
The A1C test is reported in percent: 5.7% to 6.4% indicates prediabetes. Only a clinician can interpret your results.
Source: NIDDK, Insulin Resistance and Prediabetes (checked on October 6, 2026)
- A1C: shows your average blood sugar over about the past three months. 5.7% to 6.4% indicates prediabetes.
- Fasting plasma glucose: measured after not eating for at least eight hours. 100 to 125 mg/dL indicates prediabetes.
- Oral glucose tolerance test (OGTT): blood sugar measured before and two hours after a sugary drink. A two-hour value of 140 to 199 mg/dL indicates prediabetes.
Depending on your history, a clinician may also check blood pressure, cholesterol and triglycerides, liver tests (because insulin resistance is tied to fatty liver disease) and waist size. Fasting insulin levels and calculated scores such as HOMA-IR are used in research but are not standardized for routine diagnosis, so do not be surprised if your clinician does not order them. Our waist-to-height calculator and BMI calculator give rough screening numbers to bring to the visit; they are not a diagnosis.
What the evidence says about lifestyle
The strongest evidence comes from the Diabetes Prevention Program (DPP), published in the New England Journal of Medicine in 2002. It enrolled 3,234 adults with raised blood sugar who did not have diabetes and randomly assigned them to placebo, the diabetes medicine metformin, or an intensive lifestyle program. The lifestyle program aimed for 7% weight loss and at least 150 minutes of physical activity a week. Over an average follow-up of 2.8 years:
| Item | Value |
|---|---|
| Placebo | 11 |
| Metformin | 7.8 |
| Lifestyle program | 4.8 |
3,234 adults with raised blood sugar, average 2.8 years. Lifestyle cut new cases by 58% and metformin by 31% compared with placebo.
Source: Diabetes Prevention Program Research Group, NEJM 2002 (checked on October 6, 2026)
The lifestyle program reduced new cases of diabetes by 58% compared with placebo, and metformin by 31%. To prevent one case over three years, about 7 people needed the lifestyle program, compared with about 14 for metformin. The NIDDK summarizes the practical message: losing 5% to 7% of starting weight helped reduce the chance of developing type 2 diabetes. For someone who weighs 200 pounds, that is 10 to 14 pounds.
The DPP approach is now offered nationally. The CDC’s National Diabetes Prevention Program builds a network of lifestyle change programs that last one year, in person or online, and the CDC describes the program as proven to cut type 2 diabetes risk in half. The CDC website has a program finder and an eligibility check; ask your clinician or health plan whether a program near you is covered.
The building blocks
- Movement. Muscles that work use glucose, and the DPP goal was at least 150 minutes a week of moderate activity such as brisk walking. Our walking guide has a six-week plan, and strength training builds the muscle that takes up glucose.
- A modest calorie deficit. Weight loss of 5% to 7% is the target in the evidence. The calorie deficit guide explains how to create one without extreme dieting.
- Eating pattern. No single diet is required. Patterns built on vegetables, legumes, whole grains, fish and olive oil, such as the Mediterranean diet and DASH, are common starting points; ask a registered dietitian for a plan that fits your food and budget.
- Sleep and smoking. The NIDDK lists sleep apnea and smoking among the risk factors, so treating sleep problems and quitting smoking are part of the picture.
A first conversation, in order
- Know your risk factorsUse the list above and your family history.
- Ask for a blood sugar testA1C, fasting glucose or an OGTT, as your clinician decides.
- Agree on a targetThe DPP aimed for 7% weight loss and 150 minutes of activity a week.
- Get supportAsk about a CDC-recognized lifestyle change program or a registered dietitian.
- RecheckRepeat tests on the schedule your clinician sets.
Medications that may be discussed
No medicine is FDA approved to treat “insulin resistance” as a diagnosis on its own. Medicines come into the conversation in three ways, and each has its own label and risks:
- Metformin. MedlinePlus describes metformin as a medicine used to treat type 2 diabetes. In the DPP it delayed type 2 diabetes, and the NIDDK notes it worked best for women with a history of gestational diabetes, younger adults and people with obesity. Using it for prediabetes is a decision for you and your clinician. Its information warns of a rare but serious risk called lactic acidosis, higher with kidney disease, and lists stomach side effects and possible vitamin B12 deficiency.
- Weight-management medicines. If you have obesity, or overweight with a weight-related condition, FDA-approved weight medicines such as Wegovy (semaglutide) and Zepbound (tirzepatide) may be considered. They are approved for weight management, not for insulin resistance itself. See the GLP-1 medications guide.
- Diabetes medicines. Once type 2 diabetes is diagnosed, many more options apply; they are covered on our type 2 diabetes and weight page.
In a three-year analysis of the SURMOUNT-1 trial published in the New England Journal of Medicine in 2025, 1,032 adults with obesity and prediabetes took weekly tirzepatide or placebo for 176 weeks. Type 2 diabetes was diagnosed in 1.3% of people on tirzepatide compared with 13.3% on placebo. After 17 weeks off treatment, the figures were 2.4% and 13.7%. This is trial evidence in a specific group, not a prevention approval: Zepbound’s FDA label does not list diabetes prevention as an indication.
| Item | Value |
|---|---|
| Tirzepatide (all doses) | 1.3% |
| Placebo | 13.3% |
Weight change at 176 weeks: -12.3% to -19.7% by dose vs -1.3% with placebo. Diabetes prevention is not an FDA-approved use.
Source: Jastreboff AM et al., NEJM 2025 (SURMOUNT-1, 3-year analysis) (checked on October 6, 2026)
How it links to other conditions
Insulin resistance rarely travels alone. The NIDDK lists PCOS, sleep apnea and Cushing’s syndrome among the conditions that raise the risk. It is also closely tied to fatty liver disease, high blood pressure and abnormal cholesterol, a cluster sometimes called metabolic syndrome. Our conditions hub covers each of these, and our visceral fat guide explains why fat around the organs matters more than fat elsewhere.
When to see a doctor
Ask about blood sugar testing if you have several of the risk factors above, if you had gestational diabetes, if you notice dark velvety skin patches, or if you are starting a weight-loss plan and want a baseline. See a clinician promptly if you have symptoms of high blood sugar such as unusual thirst, frequent urination, blurred vision or sores that do not heal. A primary care clinician is the usual first stop; an endocrinologist or an obesity medicine doctor may help with more complex cases.
Cost and insurance
Blood sugar tests are routine and are often covered as part of preventive care, but coverage depends on your plan, so ask before the visit. For Medicare beneficiaries, the temporary Medicare GLP-1 Bridge (July 1, 2026 to December 31, 2027) includes adults with a BMI of 27 or more plus prediabetes among its eligibility groups, with a $50 copay for Wegovy, Foundayo or Zepbound KwikPen when prescribed for weight management (checked on CMS on 2026-10-06). See our insurance hub for details.
Overview
Insulin resistance is a condition in which cells in the muscles, fat and liver do not respond well to insulin, so the pancreas makes more to keep blood sugar normal. Over time blood sugar can rise into the prediabetes and type 2 diabetes ranges. It usually has no symptoms and is closely linked to excess weight, inactivity, age and family history; losing 5% to 7% of starting weight and regular activity lowered the risk of type 2 diabetes in the Diabetes Prevention Program.
Signs
- Usually no symptoms (NIDDK)
- Acanthosis nigricans: darker, thick, velvety skin in body folds such as the neck, armpits and groin (MedlinePlus)
- If blood sugar reaches the diabetes range: more thirst and urination, hunger, blurred vision, fatigue, slow-healing sores, frequent infections (NIDDK)
Tests a clinician may order
- A1C: 5.7% to 6.4% indicates prediabetes
- Fasting plasma glucose: 100 to 125 mg/dL indicates prediabetes
- Oral glucose tolerance test: 140 to 199 mg/dL at 2 hours indicates prediabetes
- Often also: blood pressure, cholesterol and triglycerides, liver tests, waist measurement
What lifestyle research shows
In the Diabetes Prevention Program (3,234 adults, average 2.8 years), a lifestyle program aiming for 7% weight loss and 150 minutes of activity a week reduced new type 2 diabetes by 58% versus placebo (4.8 vs 11.0 cases per 100 person-years); metformin reduced it by 31%. The NIDDK summarizes that losing 5% to 7% of starting weight helped reduce the chance of developing the disease.
When to see a doctor
Ask about testing if you have several risk factors (overweight, age 35+, family history, gestational diabetes, PCOS, sleep apnea, inactivity), dark velvety skin patches, or before starting a weight-loss plan. See a clinician promptly for symptoms of high blood sugar such as unusual thirst, frequent urination, blurred vision or slow-healing sores.
Treatments discussed
FDA approved for weight managementPrescriptionInjectionWegovy (semaglutide): uses, side effects, cost and FDA statusSemaglutide: one ingredient, several brands · Injection · Weekly
FDA approved for weight managementPrescriptionInjectionZepbound (tirzepatide): uses, side effects, cost and FDA statusTirzepatide: how the dual GIP/GLP-1 drug works (Zepbound, Mounjaro) · Injection · Weekly
FDA approved for weight managementPrescriptionInjectionSemaglutide: one ingredient, several brandsInjection · Daily, Weekly
FDA approved for weight managementPrescriptionInjectionTirzepatide: how the dual GIP/GLP-1 drug works (Zepbound, Mounjaro)Injection · Weekly
FDA approved for another useOff-label use discussedPrescriptionPillRybelsus (oral semaglutide): a diabetes pill, not a weight-loss approvalSemaglutide: one ingredient, several brands · Pill (tablet) · DailyResearch mentioning it
Continuous Glucose Monitors for Weight Loss Without Diabetes: What the Evidence SaysOver-the-counter continuous glucose monitors for weight loss without diabetes: what the FDA cleared, what normal glucose…
From TOPS to Telehealth: A History of Weight-Loss ProgramsA history of weight-loss programs from company records, SEC filings, FTC cases and major trials: TOPS…
The Best Non-Prescription Weight-Loss Programs in 2026 (Ranked by Evidence)The best non-prescription weight-loss programs in 2026, ranked by published evidence: the National Diabetes Prevention Program,…Related guides
Tools for this topic
Questions to ask your doctor or pharmacist
- Based on my history, should I have an A1C, fasting glucose or glucose tolerance test, and how often?
- What do my results mean, and what number should we aim for at the next test?
- Is there a CDC-recognized lifestyle change program or a dietitian you can refer me to?
- Could any of my current medicines be affecting my blood sugar or weight?
- Should we also check my liver, blood pressure, cholesterol or sleep?
- If lifestyle changes are not enough, what are the options and their risks for me?
Frequently asked questions
Can insulin resistance be reversed?
Insulin resistance often improves with weight loss, more activity and better sleep, and blood sugar can return to the normal range. Whether it improves for a particular person, and how much, can only be checked with follow-up tests ordered by a clinician.
How do I know if I have insulin resistance?
Usually you cannot tell from symptoms. Clinicians check blood sugar with an A1C, a fasting glucose or an oral glucose tolerance test. Dark, velvety skin in body folds can be a clue, but only testing gives an answer.
Is insulin resistance the same as prediabetes?
Not exactly. Insulin resistance is the underlying problem; prediabetes is a blood sugar level above normal but below the diabetes range. Many people with insulin resistance have prediabetes, but not all.
How much weight loss helps?
The NIDDK summarizes that losing 5% to 7% of starting weight helped reduce the chance of type 2 diabetes in the Diabetes Prevention Program. For a 200-pound person, that is 10 to 14 pounds.
Is there a diet for insulin resistance?
No single diet is required. A modest calorie deficit and a pattern rich in vegetables, legumes, whole grains and lean proteins, such as the Mediterranean or DASH diet, are common starting points. A registered dietitian can tailor a plan.
Should I take metformin for insulin resistance?
Metformin is a type 2 diabetes medicine. In the Diabetes Prevention Program it lowered new diabetes by 31%, less than the lifestyle program. Whether it makes sense for you, given its side effects and your kidney function, is a decision for you and your clinician.
Do GLP-1 medicines treat insulin resistance?
They are not approved for insulin resistance itself. Wegovy and Zepbound are approved for weight management in people who meet their label criteria, and trials show they lower blood sugar. In a 3-year SURMOUNT-1 analysis, type 2 diabetes was diagnosed in 1.3% on tirzepatide vs 13.3% on placebo among people with prediabetes.
Does insulin resistance cause weight gain?
The relationship runs both ways: excess weight, especially around the waist, is a major risk factor for insulin resistance, and the NIDDK lists overweight and a large waist first among risk factors. Researchers do not fully understand the mechanisms.
Can thin people have insulin resistance?
Yes. Weight is only one risk factor. Age, family history, ethnicity, inactivity, some medicines and conditions such as PCOS also raise the risk, so testing decisions should not rest on weight alone.
References
- Insulin Resistance and Prediabetes. National Institute of Diabetes and Digestive and Kidney Diseases (NIH). (accessed October 6, 2026) Government page
- National Diabetes Statistics Report. Centers for Disease Control and Prevention, 2026. (accessed October 6, 2026) Government page
- Diabetes Prevention Program Research Group. Reduction in the Incidence of Type 2 Diabetes with Lifestyle Intervention or Metformin. New England Journal of Medicine, 2002. doi:10.1056/NEJMoa012512 · PMID 11832527 (accessed October 7, 2026) Randomized trial
- Jastreboff AM, le Roux CW, Stefanski A, et al.. Tirzepatide for Obesity Treatment and Diabetes Prevention. New England Journal of Medicine, 2025. doi:10.1056/NEJMoa2410819 · PMID 39536238 · NCT04184622 (accessed October 6, 2026) Randomized trial
- Acanthosis nigricans. MedlinePlus (National Library of Medicine). (accessed October 6, 2026) Government page
- Metformin. MedlinePlus (National Library of Medicine). (accessed October 6, 2026) Government page
- Symptoms and Causes of Diabetes. National Institute of Diabetes and Digestive and Kidney Diseases (NIH). (accessed October 6, 2026) Government page
- ZEPBOUND (tirzepatide) injection: prescribing information. Eli Lilly and Company, via DailyMed, 2026. (accessed October 7, 2026) Drug label
- National Diabetes Prevention Program. Centers for Disease Control and Prevention. (accessed October 6, 2026) Government page
- Medicare GLP-1 Bridge: Information for Part D Plans. Centers for Medicare & Medicaid Services. (accessed October 6, 2026) Government page
Facts checked on October 6, 2026
Educational information, not medical advice. Talk with a qualified healthcare professional about your own situation. In an emergency call 911.