What is Insulin Resistance?
Insulin resistance is a condition where your body's cells don't respond properly to insulin—the hormone that helps sugar (glucose) move from your blood into your cells for energy—forcing your pancreas to produce more and more insulin to keep blood sugar levels normal. 1, 2
Think of insulin as a key that unlocks your cells to let sugar in. When you have insulin resistance, the locks are "rusty"—the key still works, but you need many more keys (much more insulin) to open the same doors. 3
What Happens in Your Body
- Your pancreas initially compensates by making extra insulin to overcome this resistance, leading to high insulin levels in your blood (hyperinsulinemia) even while your blood sugar remains normal 1, 4
- Over time, your pancreas can't keep up with the demand, and blood sugar levels start to rise, potentially leading to prediabetes and eventually type 2 diabetes 1, 5
- Insulin resistance particularly affects how your muscles, liver, and fat tissue use glucose, while also disrupting fat metabolism—your body stores more fat and breaks down less of it 1, 6
Common Signs You Might Notice
- Darkened, velvety skin patches (acanthosis nigricans), typically on the neck, armpits, or groin 1, 5
- Increased belly fat or central obesity—fat concentrated around your midsection rather than evenly distributed 1, 5
- Skin tags (small flesh-colored growths) 5
- Fatigue, especially after meals 6
How is Insulin Resistance Screened?
Who Should Be Tested
You should be screened if you have a BMI ≥25 kg/m² (or ≥23 kg/m² if you're Asian American) plus any additional risk factor. 5, 7
Additional risk factors include:
- Family history: A parent or sibling with type 2 diabetes 5, 7
- Race/ethnicity: American Indian, African American, Hispanic/Latino, or Asian/Pacific Islander background 1, 5
- Physical signs: Acanthosis nigricans, central obesity, or skin tags 5, 7
- Medical conditions: High blood pressure, abnormal cholesterol, polycystic ovary syndrome (PCOS), or previous gestational diabetes 1, 5
- Lifestyle: Physical inactivity 5, 7
What Labs to Check
All testing must be done fasting (at least 8 hours without food) to get accurate results. 5, 7
Primary Tests (in order of importance):
Fasting Plasma Glucose (FPG)
Fasting Insulin Level
Hemoglobin A1C (HbA1c) - reflects average blood sugar over 2-3 months
Oral Glucose Tolerance Test (OGTT) - if initial tests are unclear
Additional Tests:
- Lipid panel to check for dyslipidemia (HDL cholesterol <35 mg/dL or triglycerides >250 mg/dL often accompany insulin resistance) 1, 5
- C-peptide can help distinguish whether high insulin is coming from your own pancreas versus injected insulin 5, 7
Critical Testing Pitfalls to Avoid
- Never test when you're acutely ill—stress from illness temporarily raises blood sugar and can falsely suggest insulin resistance 1, 7
- Normal blood sugar doesn't rule out insulin resistance—you can have high insulin levels keeping your sugar normal (this is early insulin resistance) 5, 8
- Don't rely on A1C alone—it's a secondary measure and should be combined with fasting glucose or insulin levels 1, 5
How to Manage Insulin Resistance
Lifestyle Modifications (First-Line Treatment)
Weight loss of even 5-10% of body weight significantly improves insulin sensitivity and is the cornerstone of treatment. 1
Diet Strategies:
- Limit refined carbohydrates and sugars—these cause rapid blood sugar spikes that worsen insulin resistance 1, 8
- Focus on whole foods: vegetables, lean proteins, healthy fats, and high-fiber foods 1
- Avoid hypercaloric diets—excess calories, particularly from carbohydrates, promote insulin resistance 1, 8
- Don't skip meals or fast excessively—this can worsen metabolic control 1
Physical Activity:
- Regular exercise directly improves insulin sensitivity in muscles, even without weight loss 1, 5
- Aim for at least 150 minutes of moderate activity weekly (brisk walking, swimming, cycling) 5
- Resistance training (weights) is particularly effective for building muscle mass, which improves glucose uptake 1
Medical Management
When Medications Are Needed:
If lifestyle changes don't adequately control blood sugar (fasting glucose remains >100 mg/dL or A1C >5.7%), medication should be considered. 1, 5
- Metformin is typically the first medication prescribed—it reduces liver glucose production and improves insulin sensitivity 1
- Other medications may be added based on individual circumstances and progression toward diabetes 1
Important Caveats:
- No weight-loss medications are currently approved for children and adolescents with insulin resistance alone 1
- Avoid "quick fix" diets or unproven supplements—they rarely provide lasting benefit and may cause harm 1
- Medications work only while you're taking them—lifestyle changes remain essential for long-term success 1
Monitoring and Follow-Up
- Recheck fasting glucose and A1C every 1-3 years depending on your risk level 1, 5
- Monitor blood pressure and cholesterol annually, as these often worsen alongside insulin resistance 1, 5
- Screen for complications like fatty liver disease if insulin resistance persists 1
Special Population Considerations
- Asian Americans should be screened at lower BMI thresholds (≥23 kg/m² instead of ≥25 kg/m²) due to higher diabetes risk at lower weights 5, 7
- Women with previous gestational diabetes have significantly elevated risk and need closer monitoring 1, 5
- Children at risk should be screened starting at age 10 or at puberty onset, whichever comes first 1