Insulin resistance and HOMA IR
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How is HOMA-IR calculated from fasting glucose and insulin?
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Insulin resistance and HOMA IR
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"Insulin Resistance"[MeSH Terms] AND HOMA
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HOMA-IR calculation fasting glucose insulin official clinical source
HOMA-IR stands for Homeostatic Model Assessment of Insulin Resistance. It is a fasting blood-test estimate of how resistant the body is to insulin. A higher value generally suggests greater insulin resistance.
Calculation
Use fasting glucose and fasting insulin drawn at the same time:
- If glucose is in mmol/L and insulin is in µIU/mL (or mU/L):
[
\text{HOMA-IR}=\frac{\text{fasting insulin} \times \text{fasting glucose}}{22.5}
]
- If glucose is in mg/dL and insulin is in µIU/mL:
[
\text{HOMA-IR}=\frac{\text{fasting insulin} \times \text{fasting glucose}}{405}
]
Example: fasting insulin 12 µIU/mL and glucose 90 mg/dL:
[
(12 \times 90) / 405 = 2.67
]
Interpretation
There is no universal diagnostic cut-off. Results vary with age, ethnicity, body size, assay method, and population studied. In some research and clinical settings, values around >2 to 2.5 may be considered compatible with insulin resistance, but the laboratory and clinician should interpret it in context. One textbook example cites >2.3, but this is not a universal threshold. HOMA-IR is an indirect estimate, not the reference-standard test. The euglycemic hyperinsulinemic clamp is the research gold standard. Fuster and Hurst's The Heart, 15th Edition, block 3, lines 1219-1226.
For the most meaningful result, testing is generally done after an overnight fast, without acute illness, and interpreted together with glucose or HbA1c, lipids, blood pressure, waist/BMI, medications, and conditions such as PCOS or fatty liver. The NCBI overview of insulin-sensitivity assessment describes the mmol/L formula and the limitations of fasting surrogate measures.
Insulin resistance
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"Insulin Resistance"[MeSH Terms]
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NIDDK insulin resistance symptoms causes prevention diagnosis
Insulin resistance means that the body’s muscle, fat, and liver cells do not respond normally to insulin. Insulin is the hormone that helps glucose move from blood into cells for energy.
At first, the pancreas compensates by producing more insulin, so blood glucose can remain normal. Over time, this compensation may fail, causing prediabetes and then type 2 diabetes. NIDDK explains this progression.
Common associations and risk factors
- Excess abdominal body fat or weight gain
- Physical inactivity
- Family history of type 2 diabetes
- Polycystic ovary syndrome (PCOS)
- Previous gestational diabetes
- Fatty liver disease
- Smoking
- Some medications, especially glucocorticoids
- Certain endocrine disorders, such as Cushing syndrome
Symptoms
Insulin resistance itself often causes no obvious symptoms. Possible clues include:
- Increasing waist circumference
- Elevated triglycerides or low HDL cholesterol
- High blood pressure
- Prediabetes or high fasting glucose/HbA1c
- Dark, velvety skin thickening in the neck, groin, or armpits, called acanthosis nigricans
Tests
There is no single routine diagnostic test. Clinicians usually assess:
- Fasting plasma glucose and HbA1c
- Lipid profile
- Blood pressure, waist circumference, and weight
- Sometimes fasting insulin and HOMA-IR
[
\text{HOMA-IR}=\frac{\text{fasting insulin (µIU/mL)} \times \text{fasting glucose (mg/dL)}}{405}
]
Or, when glucose is measured in mmol/L:
[
\text{HOMA-IR}=\frac{\text{fasting insulin (µIU/mL)} \times \text{fasting glucose (mmol/L)}}{22.5}
]
HOMA-IR is an estimate rather than a definitive diagnostic test, and its cut-off varies by laboratory and population. The euglycemic hyperinsulinemic clamp is the research reference standard. Fuster and Hurst's The Heart, 15th Edition, block 3, lines 1219-1226.
What helps
- Sustained weight loss if overweight. Even modest loss can improve insulin sensitivity.
- Regular activity: aerobic exercise plus resistance training.
- A dietary pattern based on minimally processed foods, vegetables, legumes, whole grains, protein sources, and unsweetened drinks.
- Adequate sleep and treatment of sleep apnea if present.
- Avoiding smoking.
- Treating related conditions such as high blood pressure, dyslipidemia, prediabetes, PCOS, or diabetes. Medicines may be appropriate in selected people, but depend on the individual condition and risk profile.
Recent systematic-review evidence continues to link insulin resistance with cardiometabolic risk, but it does not change the core approach of assessing glucose status and addressing modifiable risk factors.
HOMA IR
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"Insulin Resistance"[MeSH Terms] AND HOMA
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HOMA-IR fasting insulin glucose formula clinical reference
HOMA-IR means Homeostatic Model Assessment of Insulin Resistance. It is a calculated estimate of insulin resistance using fasting insulin and glucose levels.
Formula
If fasting glucose is in mg/dL:
[
\text{HOMA-IR}=\frac{\text{fasting insulin (µIU/mL)} \times \text{fasting glucose (mg/dL)}}{405}
]
If fasting glucose is in mmol/L:
[
\text{HOMA-IR}=\frac{\text{fasting insulin (µIU/mL)} \times \text{fasting glucose (mmol/L)}}{22.5}
]
Example
Fasting insulin = 10 µIU/mL
Fasting glucose = 90 mg/dL
Fasting glucose = 90 mg/dL
[
\frac{10 \times 90}{405}=2.22
]
Meaning
Higher HOMA-IR generally indicates lower insulin sensitivity, meaning more insulin resistance. However, there is no single universal cut-off because values differ by laboratory insulin assay, ethnicity, age, weight, and clinical population. Some studies use values around 2 to 2.5 or higher as a possible indicator, but it should not diagnose insulin resistance on its own.
It is best interpreted alongside HbA1c, fasting glucose, triglycerides, HDL cholesterol, waist circumference, body weight, blood pressure, and conditions such as PCOS or fatty liver disease. HOMA-IR is a practical indirect estimate; the research reference method is the euglycemic insulin clamp. Fuster and Hurst's The Heart, 15th Edition, block 3, lines 1219-1226.
Subclinical atherosclerosis
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"subclinical atherosclerosis"
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subclinical atherosclerosis coronary artery calcium carotid plaque guideline prevention ACC AHA
Subclinical atherosclerosis is early plaque buildup in arteries before it causes symptoms such as angina, heart attack, stroke, or peripheral artery disease.
It means a person may feel well but already have structural evidence of artery disease. It is a marker of increased future cardiovascular risk.
How it is detected
Common noninvasive tests include:
- Coronary artery calcium (CAC) scan: a low-radiation CT scan that measures calcified plaque in coronary arteries. A CAC score above 0 indicates coronary atherosclerosis.
- Carotid ultrasound: can identify carotid plaque and sometimes measure carotid intima-media thickness.
- CT coronary angiography: can show both calcified and noncalcified coronary plaque, but is not usually a general screening test.
- Ankle-brachial index: detects peripheral arterial disease, which may coexist with systemic atherosclerosis.
CAC and carotid ultrasound are recognized noninvasive measures of subclinical atherosclerosis. The 2024 review of assessment methods discusses their roles in asymptomatic people.
Who may benefit from assessment
Testing is not routine for everyone. It can be considered when treatment decisions are uncertain, especially in people with borderline or intermediate estimated cardiovascular risk, a strong family history of premature cardiovascular disease, diabetes, smoking history, chronic kidney disease, or risk-enhancing lipid results such as elevated lipoprotein(a).
Current ACC/AHA guidance supports selective CAC scanning to refine risk and help decide on preventive lipid-lowering therapy in appropriate adults. The ACC summary of the 2026 guideline notes its use for early calcium and plaque detection when risk remains uncertain.
Why it matters
Subclinical disease is an opportunity for prevention:
- Stop smoking or avoid tobacco exposure
- Control blood pressure, diabetes, and sleep apnea
- Lower LDL cholesterol when indicated
- Regular aerobic and resistance activity
- Diet centered on vegetables, fruit, legumes, whole grains, nuts, and minimally processed foods
- Maintain or work toward a healthy weight
A CAC score of 0 often indicates lower near-term coronary risk, but does not rule out noncalcified plaque or eliminate risk, particularly in smokers, people with diabetes, or those with a strong family history.
Coronary microvascular dysfunction and chronic coronary syndrome
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"coronary microvascular dysfunction" AND "chronic coronary syndrome"
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2024 ESC chronic coronary syndromes guideline coronary microvascular dysfunction ANOCA INOCA diagnosis treatment
Coronary microvascular dysfunction and chronic coronary syndrome
Chronic coronary syndrome (CCS) describes stable or recurring symptoms caused by chronic disease of the coronary arteries or the heart’s small coronary vessels. It includes obstructive coronary artery disease, but also angina or ischaemia without obstructive epicardial coronary stenosis, termed ANOCA/INOCA.
Coronary microvascular dysfunction (CMD) is impaired regulation of blood flow in the heart’s small arteries and arterioles. These vessels cannot be directly seen on routine coronary angiography. CMD can reduce myocardial blood supply during stress or exertion even when the major coronary arteries appear normal or only mildly diseased.
The 2024 ESC CCS guideline explicitly includes ANOCA/INOCA diagnosis and management within CCS.
How CMD presents
Possible symptoms include:
- Pressure, tightness, burning, heaviness, or discomfort in the chest
- Breathlessness, reduced exercise tolerance, fatigue
- Symptoms with physical exertion, mental stress, or sometimes at rest
- Symptoms that may persist longer than classic obstructive-coronary angina and may respond inconsistently to nitrates
CMD is more often recognized in women, but occurs in all sexes. It can coexist with obstructive coronary disease, hypertension, diabetes, chronic kidney disease, obesity, inflammatory disease, HFpEF, or coronary vasospasm.
CMD versus obstructive coronary disease
| Feature | Obstructive epicardial CAD | CMD / microvascular angina |
|---|---|---|
| Main site | Large coronary arteries | Small intramyocardial arteries and arterioles |
| Angiogram | May show flow-limiting narrowing | Often normal or nonobstructive |
| Mechanism | Plaque-related narrowing | Impaired dilation, increased microvascular resistance, endothelial dysfunction, or microvascular spasm |
| Treatment | Prevention, antianginals, sometimes PCI/CABG | Prevention plus phenotype-directed antianginal therapy; PCI does not treat isolated CMD |
CMD is not “nothing” or merely anxiety. It can be associated with persistent symptoms, impaired quality of life, and higher cardiovascular risk. A recent systematic review and meta-analysis found prognostic significance for isolated coronary microvascular disease, although risks and test thresholds depend on the patient population and diagnostic method.
Diagnosis
Diagnosis usually proceeds in stages:
-
Exclude or define obstructive coronary disease
- ECG, echocardiography, stress imaging, coronary CT angiography, or invasive angiography may be used based on symptoms and pre-test likelihood.
- If a narrowing is seen, invasive physiologic assessment such as FFR or iFR can determine whether it is flow-limiting.
-
Demonstrate impaired microvascular function or microvascular spasm
- Noninvasive: stress PET myocardial blood-flow reserve, stress cardiac MRI perfusion, or Doppler coronary flow reserve in selected centers.
- Invasive coronary function testing: coronary flow reserve (CFR), index of microcirculatory resistance (IMR), and acetylcholine provocation testing for epicardial or microvascular spasm.
An IMR of 23 or higher is described as abnormal and consistent with CMD; reduced CFR together with increased IMR is more specific for CMD. Braunwald’s Heart Disease, 2 Vol Set: A Textbook of Cardiovascular Medicine, block 3, lines 83-84.
Treatment principles
Treatment should be individualized according to the identified mechanism, whether impaired vasodilation, increased microvascular resistance, microvascular spasm, epicardial spasm, obstructive CAD, or a combination.
For everyone with CCS/CMD
- Stop smoking or vaping nicotine.
- Control blood pressure, LDL cholesterol, diabetes, body weight, sleep apnea, and physical inactivity.
- Regular, graded aerobic activity and resistance training as tolerated.
- Mediterranean-style or similarly heart-healthy eating pattern.
- Address stress, depression, and sleep problems, which can worsen angina symptoms.
- Use statins, ACE inhibitors/ARBs, antiplatelet therapy, and other preventive medications when individually indicated by overall cardiovascular risk and coronary anatomy.
Antianginal therapy
- Beta-blockers are commonly used when the dominant issue is reduced flow reserve or increased demand, especially with high heart rate.
- Calcium-channel blockers are usually preferred when vasospasm is present or strongly suspected.
- Long-acting nitrates may help some people but can be less consistently effective in isolated CMD.
- Ranolazine, ivabradine, and other antianginals may be considered in selected patients with persistent symptoms.
- If testing identifies vasospastic angina, avoiding smoking and vasoconstricting substances is particularly important.
A 2025 review of CMD therapies supports phenotype-directed treatment but also reflects that no single medication works equally well for every CMD subtype.
Key takeaway
A normal coronary angiogram does not exclude a coronary cause of angina. In a person with ongoing exertional chest symptoms or objective ischaemia and no obstructive stenosis, CMD and vasospasm should be considered, ideally with referral to a cardiologist or an INOCA/CMD-focused center.
Seek urgent emergency assessment for new, severe, prolonged, or worsening chest pressure, especially with breathlessness, sweating, nausea, fainting, or pain radiating to the arm, jaw, back, or shoulder.
What is sensitivity and specificity
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sensitivity specificity diagnostic test definitions CDC
Sensitivity and specificity describe how well a diagnostic test distinguishes people with a condition from people without it.
| Actual condition | Test positive | Test negative |
|---|---|---|
| Disease present | True positive (TP) | False negative (FN) |
| Disease absent | False positive (FP) | True negative (TN) |
Sensitivity
The ability of a test to correctly identify people who have the disease.
[
\text{Sensitivity} = \frac{TP}{TP+FN}
]
- A highly sensitive test has few false negatives.
- A negative result from a very sensitive test helps rule out disease.
- Memory aid: SnNout: Sensitive test, Negative result, rules OUT.
Example: Of 100 people who truly have a disease, a test detects 95.
[
\text{Sensitivity} = 95/100 = 95%
]
Specificity
The ability of a test to correctly identify people who do not have the disease.
[
\text{Specificity} = \frac{TN}{TN+FP}
]
- A highly specific test has few false positives.
- A positive result from a very specific test helps rule in disease.
- Memory aid: SpPin: Specific test, Positive result, rules IN.
Example: Of 100 people who do not have a disease, the test correctly reports 90 as negative.
[
\text{Specificity} = 90/100 = 90%
]
Important distinction
Sensitivity and specificity are properties of the test itself and do not directly depend on disease prevalence. In contrast, positive predictive value and negative predictive value answer what a positive or negative result means for an individual patient, and they do depend strongly on how common the condition is in the tested population.
The CDC diagnostic-test guide uses the same definitions of sensitivity as correct identification of disease and specificity as correct identification of absence of disease.
What is area under curve and hazard ratio and odds ratio
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"Hazard Ratio"[MeSH Terms] AND "Odds Ratio"[MeSH Terms]
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area under ROC curve hazard ratio odds ratio definitions NCBI
1. Area under the curve (AUC)
Usually refers to the area under the receiver operating characteristic (ROC) curve. It measures how well a test or prediction model distinguishes between two groups, such as people with versus without disease.
- ROC curve plots:
- Sensitivity on the y-axis
- 1 - specificity (false-positive rate) on the x-axis
- AUC ranges from 0 to 1:
- 0.50: no discrimination, equivalent to chance
- 0.70 to 0.79: acceptable discrimination
- 0.80 to 0.89: good discrimination
- 0.90 or above: excellent discrimination
- 1.00: perfect discrimination
Another useful interpretation: an AUC of 0.80 means the model assigns a higher predicted risk to a randomly chosen person with the outcome than to a randomly chosen person without it about 80% of the time.
AUC indicates discrimination, not whether the predicted probabilities are well calibrated or whether a test improves outcomes. See this ROC overview.
2. Odds ratio (OR)
An odds ratio compares the odds of an outcome between two groups. It is common in case-control studies and logistic regression.
[
\text{Odds ratio}=\frac{\text{odds of outcome in exposed group}}{\text{odds of outcome in unexposed group}}
]
Interpretation:
- OR = 1: no association
- OR > 1: higher odds of the outcome in the exposed group
- OR < 1: lower odds of the outcome in the exposed group
Example: OR = 2.0 for smoking and a disease means the smoking group has twice the odds of that disease compared with the nonsmoking group.
Important: an OR is not automatically the same as risk ratio. When an outcome is common, odds ratios can look larger than the corresponding relative risk.
3. Hazard ratio (HR)
A hazard ratio compares the rate at which an event happens over time between two groups. It is used in survival or time-to-event analyses, such as time to death, heart attack, cancer recurrence, or hospital admission.
[
\text{HR}=\frac{\text{instantaneous event rate in group A}}{\text{instantaneous event rate in group B}}
]
Interpretation:
- HR = 1: no difference in event rate over follow-up
- HR = 1.5: at a given point during follow-up, one group has a 50% higher event rate
- HR = 0.70: one group has a 30% lower event rate
Example: HR 0.70 (95% CI 0.55-0.89) for a medication versus placebo means the medication group had an estimated 30% lower instantaneous rate of the event during the study period. Since the confidence interval does not include 1, the result is conventionally statistically significant at the 0.05 level.
Quick comparison
| Measure | Main question answered | Common use |
|---|---|---|
| AUC | How well does a test/model distinguish outcomes? | Diagnostic and prediction models |
| OR | How do the odds of an outcome differ between groups? | Case-control studies, logistic regression |
| HR | How do event rates differ over time? | Cohort studies, clinical trials, survival analysis |
For OR and HR, the 95% confidence interval is essential. A confidence interval that crosses 1.0 means the study data are compatible with no difference between groups.
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