Complete Testing & Optimization Guide
Optimal ranges, provider comparison, and strategies to improve your Insulin levels
Included in 7 of 10 major testing providers
Metabolic Health / Glucose
Fasting:2.6-24.9 μIU/mL, Optimal:<10 μIU/mL
Abnormal Insulin levels can indicate underlying health issues that may go undetected without proper testing. Regular monitoring helps catch problems early when they're most treatable.
Understanding your Insulin levels enables targeted interventions, tracks treatment effectiveness, and helps optimize your overall health and performance.
Insulin is a peptide hormone produced by beta cells in the pancreas in response to rising blood glucose (after meals). Insulin's primary job is to shuttle glucose from the bloodstream into cells (muscle, fat, liver) for energy or storage. It also promotes fat storage, suppresses lipolysis (fat breakdown), and inhibits gluconeogenesis (liver glucose production). Measuring fasting insulin provides critical insight into insulin resistance—the condition where cells become less responsive to insulin, forcing the pancreas to produce more insulin to maintain normal blood glucose.
Here's the critical insight:insulin rises YEARS before glucose. In the progression toward type 2 diabetes, the pancreas compensates for insulin resistance by secreting more and more insulin to keep glucose normal. You can have perfectly normal fasting glucose (70-90 mg/dL) and HbA1c (<5.7%) while having dangerously high insulin (>10 mcIU/mL), indicating severe insulin resistance and metabolic dysfunction. By the time fasting glucose rises above 100 mg/dL, you've already had insulin resistance for 5-10 years, and your beta cells are starting to fail. Measuring fasting insulin catches metabolic disease a decade earlier than glucose or HbA1c.
HOMA-IR (Homeostatic Model Assessment of Insulin Resistance) is the gold standard calculated marker:(Fasting Glucose × Fasting Insulin) / 405. HOMA-IR >2.0 indicates insulin resistance;>2.5 is concerning;>5.0 is severe. HOMA-IR is more sensitive than glucose or HbA1c for detecting early metabolic dysfunction and predicts future diabetes, cardiovascular disease, and all-cause mortality.
Bottom line: TSH and Free T4 alone miss people with conversion problems. Free T3 is the only way to know if you have enough active thyroid hormone at the tissue level.
| Range Type | Level | Clinical Significance |
|---|---|---|
| Optimal (Longevity) | <5 mcIU/mL (fasting) | Exceptional insulin sensitivity. Associated with longevity, low CVD risk, optimal metabolic health. Target for healthspan optimization. |
| Good (Standard) | 5-7 mcIU/mL | Normal insulin sensitivity. Acceptable for most people but room for improvement with lifestyle optimization. |
| Suboptimal (Early Insulin Resistance) | 7-10 mcIU/mL | Mild insulin resistance. Beta cells compensating to maintain normal glucose. Intervene NOW with diet, exercise, weight loss to reverse. |
| Insulin Resistance | 10-15 mcIU/mL | Moderate insulin resistance. HOMA-IR likely >2.5. High risk of progressing to prediabetes/diabetes. Requires aggressive lifestyle intervention. |
Standard lab range:Fasting:2.6-24.9 μIU/mL, Optimal:<10 μIU/mL
>15 mcIU/mL
Very High (Beta Cell Failure)
Very high insulin (>20)=severe resistance. If insulin starts DROPPING despite worsening glucose, beta cells are failing (advanced diabetes).
Low-carb or ketogenic diet:Restrict carbs to <100 g/day (low-carb) or <50 g/day (keto). Eliminates insulin spikes, depletes liver glycogen, forces fat oxidation. Lowers insulin by 30-50% within weeks.
Intermittent fasting (IF):16:8 (fast 16 hours, eat within 8-hour window) or alternate-day fasting. Fasting drops insulin to baseline, enhances insulin sensitivity, promotes autophagy.
Eliminate processed carbs and sugar:White bread, pasta, rice, sugary drinks, desserts spike insulin. Replace with whole foods, vegetables, protein, healthy fats.
Prioritize protein and fiber:Protein (1.6-2.2 g/kg) preserves muscle during weight loss. Fiber (25-35 g/day) slows glucose absorption, reducing insulin spikes.
Resistance training:THE most effective exercise for improving insulin sensitivity. Heavy compound lifts (squats, deadlifts, bench) 3-4x/week build muscle, which is metabolically active and glucose-hungry. Increases GLUT4 receptors (glucose transporters) in muscle.
High-intensity interval training (HIIT):20-30 min sessions 2-3x/week improve insulin sensitivity more than steady-state cardio. Depletes muscle glycogen, forcing insulin-independent glucose uptake.
Post-meal walks:10-15 min walk after meals lowers post-meal glucose and insulin by 20-30%. Simple and effective.
Note: Lose 5-10% body weight:Even modest weight loss dramatically improves insulin sensitivity. Losing 10 kg (22 lbs) reduces fasting insulin by 30-40%. | Target visceral fat:Visceral (belly) fat is metabolically toxic, secreting inflammatory cytokines and free fatty acids that worsen insulin resistance. Measure waist circumference;goal <40 inches (men), <35 inches (women). | Calorie deficit + resistance training:Preserve muscle mass while losing fat. Muscle is insulin-sensitive;fat (especially visceral) is insulin-resistant.
Note: Metformin:500-1000 mg twice daily. First-line medication for insulin resistance and prediabetes. Reduces hepatic glucose production, improves insulin sensitivity, aids weight loss. Lowers fasting insulin by 20-30%. | Evidence:Diabetes Prevention Program showed metformin reduces diabetes incidence by 31% in prediabetics (lifestyle changes were more effective at 58%). | Side effects:GI upset (diarrhea, nausea) in 20-30%, usually resolves. Start low (500 mg once daily), titrate up. May lower B12—supplement or check annually.
Low insulin is rare and usually indicates:|Type 1 diabetes:Autoimmune destruction of pancreatic beta cells. No insulin production. Requires exogenous insulin replacement.|Advanced type 2 diabetes with beta cell failure:After years of hyperinsulinemia, beta cells burn out and insulin production drops. Glucose rises dramatically.|Hypopituitarism:Pituitary failure reduces growth hormone and other hormones that stimulate insulin secretion.
Source:Low insulin with high glucose=beta cell failure (type 1 or advanced type 2 diabetes). Requires insulin therapy.
Type 1 diabetes:Autoimmune destruction of pancreatic beta cells → no insulin production → high glucose, low/absent insulin.|Advanced type 2 diabetes with beta cell exhaustion:After years of compensatory hyperinsulinemia, beta cells fail → insulin production drops → glucose rises.|Insulinoma (very rare):Insulin-secreting pancreatic tumor causes episodic hypoglycemia with inappropriately high insulin. Diagnosed with supervised fasting test.|Exogenous insulin use:Type 1 diabetics or advanced type 2 diabetics on insulin therapy will have high measured insulin.
Source:Baseline:Check fasting insulin (with fasting glucose) if risk factors for insulin resistance:overweight/obesity, family history of diabetes, PCOS, metabolic syndrome, fatty liver.|Calculate HOMA-IR:(Fasting Glucose mg/dL × Fasting Insulin mcIU/mL) / 405. HOMA-IR >2.0=insulin resistance;>2.5=significant;>5.0=severe.|After lifestyle intervention:Retest fasting insulin and glucose after 3-6 months of diet, exercise, weight loss. Expect 30-50% drop in insulin with successful intervention. Goal:insulin <7 mcIU/mL, HOMA-IR <2.0.|If starting metformin:Retest after 3 months. Metformin should lower fasting insulin by 20-30%.|Annual screening:For anyone with prediabetes, metabolic syndrome, PCOS, or strong family history of diabetes.|Fasting required:Must fast 8-12 hours (water only). Test in morning. No food, coffee, or supplements before test.
Fasting insulin rises 5-10 years before glucose becomes abnormal. Studies show elevated insulin (>10 mcIU/mL) predicts type 2 diabetes development with 3-4x higher risk over next decade, even with normal glucose. HOMA-IR >2.5 predicts diabetes with 5-6x higher risk. Measuring insulin catches pre-diabetes much earlier than glucose or HbA1c.
Source:Tabak AG, et al. Trajectories of glycemia, insulin sensitivity, and beta cell function before diagnosis of type 2 diabetes. Lancet. 2009;373(9682):2215-2221.
Elevated fasting insulin independently predicts cardiovascular events (heart attack, stroke) and CVD mortality, even after adjusting for glucose, BMI, and other risk factors. Meta-analyses show each 5 mcIU/mL increase in fasting insulin associated with 20-30% higher CVD risk. Insulin promotes atherosclerosis, hypertension, and vascular smooth muscle proliferation.
Source:Despres JP, et al. Hyperinsulinemia as an independent risk factor for ischemic heart disease. N Engl J Med. 1996;334(15):952-957.
Insulin resistance in the brain impairs glucose metabolism and promotes amyloid-beta accumulation. Alzheimer's is increasingly called "Type 3 Diabetes."High insulin and HOMA-IR associated with 2-3x higher dementia risk. Metformin and lifestyle interventions that improve insulin sensitivity may reduce Alzheimer's risk.
Source:De la Monte SM, Wands JR. Alzheimer's disease is type 3 diabetes. J Diabetes Sci Technol. 2008;2(6):1101-1113.
| Provider | Includes Test | Annual Cost | Total Biomarkers |
|---|---|---|---|
 Superpower | ✓ | $199 | 100+ |
 WHOOP Advanced Labs | — | $349 | 65 |
 Labcorp OnDemand | — | $398 | 30+ |
| ✓ | $486 | 40+ | |
| — | $468 | 83 | |
| ✓ | $798 | 100+ | |
 InsideTracker | ✓ | $680 | 48 |
 Function Health | ✓ | $499 | 100+ |
| ✓ | $900 | 70+ | |
| ✓ | $1150 | 110 | |
| — | $Varies | 75+ |
Choose from 7 providers that include this biomarker in their panels
Insulin is a metabolic health / glucose biomarker that Hormone that regulates blood sugar The normal reference range is Fasting:2.6-24.9 μIU/mL, Optimal:<10 μIU/mL. Regular testing helps track changes and identify potential health issues early.
7 out of 10 major blood testing providers include Insulin in their standard panels. These include Superpower, Blueprint, Mito Health and others.
For most people, testing Insulin 2-4 times per year is recommended to establish baseline levels and track trends. If you have abnormal results or are actively working to optimize this biomarker, more frequent testing (quarterly) may be beneficial. Always consult with your healthcare provider for personalized testing frequency recommendations.
The standard laboratory reference range for Insulin is Fasting:2.6-24.9 μIU/mL, Optimal:<10 μIU/mL. However, many functional medicine practitioners recommend tighter "optimal" ranges for peak health and performance. Your ideal range may vary based on your age, sex, health goals, and other individual factors. Work with a healthcare provider familiar with optimal ranges to determine your target levels.
Most direct-to-consumer blood testing services that include Insulin provide the physician order as part of their service. However, some states have restrictions on direct-to-consumer testing. Check with your chosen provider about availability in your state and whether they provide the necessary physician authorization.
Elevated fasting insulin indicates insulin resistance before blood sugar rises. Early marker of metabolic dysfunction and diabetes risk. Essential for assessing metabolic health.
This information is for educational purposes only and is not medical advice. Always consult with a qualified healthcare provider about your specific health needs and before making decisions about blood testing.
