| Marker | Gabriel optimal | Typical lab range | Functional range |
|---|---|---|---|
| Fasting Insulin | 2 to 5 uIU/mL | 2.6 to 24.9 | 2 to 5 |
The tests clinicians use
| Test | What it shows | Notes |
|---|---|---|
| Fasting insulin | How much insulin your body needs at rest | High insulin with normal glucose can mean your cells aren't responding normally to insulin. Fast 8 to 12 hours. |
| HOMA-IR | An estimate of insulin resistance calculated from fasting insulin and fasting glucose | Simple and needs only a fasting blood draw; cutoffs vary by lab. |
| Fasting glucose | Blood sugar after fasting | 100 to 125 mg/dL is the prediabetes range. |
| A1C | Average blood sugar over about 3 months | 5.7 to 6.4% is the prediabetes range. Can miss prediabetes with some health conditions. |
| Triglyceride to HDL ratio | A rough marker from a standard lipid panel | Comes from a standard lipid panel; accuracy varies by ethnicity and sex. |
| Oral glucose tolerance test (OGTT) | Blood sugar measured after you drink a sugary liquid | 140 to 199 mg/dL is the prediabetes range. |
Gabriel's optimal range for fasting insulin is shown in the table on this page. See the fasting insulin, HOMA-IR and insulin resistance panel lab guides for more.
Why glucose and A1C can look normal
In early insulin resistance, the pancreas makes extra insulin and keeps blood sugar in range. Over time it may not keep up, and glucose and A1C start to rise. That is why fasting insulin can flag the problem before glucose does.
Insulin resistance also shifts blood fats. Triglycerides tend to rise and HDL to fall, which is why the triglyceride to HDL ratio works as a rough stand-in. In a 2024 review of 32 studies, it worked better in men than women and was less reliable in African American people, so it is best read alongside other tests.
Who should ask about testing
- Overweight, obesity, or a large waist
- Age 35 or older
- A family history of diabetes
- Little physical activity, smoking or vaping
- Past gestational diabetes or a baby who weighed 9 pounds or more
- PCOS, sleep apnea or Cushing's syndrome
- Long-term glucocorticoids, some antipsychotics or some HIV medicines
- Darkened, velvety skin on the neck or armpits (acanthosis nigricans), or skin tags
What helps after a positive result
Lifestyle comes first. Eating more whole foods and fewer refined carbohydrates, regular activity and losing excess weight can lower insulin resistance. In the Diabetes Prevention Program, people at high risk who lost 5 to 7% of their starting weight lowered their chance of getting type 2 diabetes. Metformin also lowered the chance in that study, though less than lifestyle changes did, and your clinician decides whether medicine belongs in your plan.
For food ideas, see foods that lower A1C and how to lower A1C. If you have prediabetes, get tested for type 2 diabetes every year.
Insulin resistance usually has no symptoms. See a clinician promptly for increased thirst, frequent urination, blurred vision or unexplained weight loss, or for episodes of low blood sugar: a high insulin with a low glucose has other possible causes that need their own workup. Call 911 for fainting or a seizure.
Common questions
What is the best test for insulin resistance?
The hyperinsulinemic-euglycemic clamp is the gold standard but is used mostly in research. In practice, fasting insulin with fasting glucose (and HOMA-IR) plus A1C and a lipid panel give a practical picture.
What is HOMA-IR?
It is a score calculated from your fasting insulin and fasting glucose that estimates insulin resistance. Higher means more resistance, but cutoffs vary by lab.
Can you have insulin resistance with a normal A1C?
Yes. Early on, the pancreas makes extra insulin and keeps glucose and A1C normal. A high fasting insulin can be the first sign.
Do I need to fast for an insulin test?
Usually yes, for 8 to 12 hours. Stop biotin supplements at least a day before, since biotin can affect the result.
Does a high triglyceride to HDL ratio mean insulin resistance?
It can point that way, but it is a rough marker. Its accuracy varies by sex and ethnicity, so it is best read with fasting insulin, glucose and A1C.
Sources
- Insulin Resistance & Prediabetes National Institute of Diabetes and Digestive and Kidney Diseases
- Insulin in Blood Test MedlinePlus, U.S. National Library of Medicine
- Insulin Resistance: What It Is, Causes, Symptoms & Treatment Cleveland Clinic
- The Triglyceride/HDL Ratio as a Surrogate Biomarker for Insulin Resistance (Baneu et al., 2024) Biomedicines
This guide is general information, not medical advice. It does not replace a visit with a licensed clinician. Gabriel membership is not health insurance.