Insulin & Metabolic Sensitivity

A deeper look into how your body responds to glucose and insulin — revealing risks of prediabetes, metabolic dysfunction, and longevity impact.

Insulin & Metabolic Sensitivity

Table of contents

Basic data

This panel goes beyond basic glucose snapshots and helps identify early signs of insulin resistance — even in individuals with normal fasting glucose or HbA1c. It typically includes fasting insulin, HOMA-IR index, C-peptide, and sometimes OGTT (oral glucose tolerance test).

Insulin resistance is a key driver of metabolic syndrome, weight gain, cardiovascular disease, and accelerated aging. Early detection allows for more proactive intervention — often through lifestyle changes alone.

Category: Lab blood panel

Level: Intermediate

Usefulness: High

Level

Intermediate

This test is recommended for intermediate users who have already optimized foundational health habits (e.g., diet, exercise, sleep). It’s a valuable next step for those looking to personalize nutrition, monitor carbohydrate tolerance, or evaluate metabolic health beyond basic glucose tests.

Usefulness

High

Measuring insulin and metabolic sensitivity provides insights missed by standard glucose panels — especially in the early stages of dysfunction, when lifestyle interventions are most effective.
Detects insulin resistance early

Fasting glucose may remain normal for years despite underlying insulin resistance. Measuring fasting insulin and HOMA-IR reveals dysfunction before it progresses.

Enables targeted dietary strategies

Results can inform dietary choices (e.g., carb tolerance, meal timing, fasting) and optimize strategies for fat loss or longevity.

How it works

Insulin sensitivity is typically evaluated through blood biomarkers related to how the body responds to glucose — often under fasting conditions.
Fasting insulin

A single blood draw taken after an overnight fast. High levels suggest early-stage insulin resistance.

HOMA-IR index

Calculated from fasting insulin and glucose. A widely used indicator of insulin resistance in research and clinical practice.

Optional - OGTT or dynamic response

In some cases, glucose and insulin are measured at intervals after consuming a glucose drink — offering additional insight into real-time glucose metabolism.

Measures

These markers help assess how effectively your body maintains glucose balance — a cornerstone of healthy aging.
Fasting insulin

Indicates baseline insulin demand. Elevated levels signal that the body needs more insulin to regulate glucose — a sign of decreased sensitivity.

HOMA-IR

Homeostatic Model Assessment of Insulin Resistance. A composite score calculated from fasting insulin and glucose.

C-peptide (optional)

Reflects insulin secretion and can help differentiate between insulin resistance and insulin production problems.

OGTT with insulin (optional)

Tracks glucose and insulin levels over 2–3 hours after consuming a sugar solution. Offers a more dynamic view of metabolic response.

Reliability

These tests are considered reliable and widely used in both clinical practice and research. However, results can vary with diet, stress, and sleep quality.
Requires proper fasting

At least 8–12 hours of fasting is essential for valid results. Even small snacks or coffee can distort fasting insulin.

May vary based on short-term habits

A single test provides a snapshot. Repeat testing or trend tracking offers a more reliable assessment of long-term status.

Limitations

While highly informative, this test has some constraints — especially when used in isolation.
Snapshot rather than full picture

One-time fasting measures may not reflect post-meal metabolism or daily insulin dynamics.

Interpretation can be nuanced

Normal values vary by lab and population. Optimal longevity-related targets may differ from clinical reference ranges.

Frequency

Suggested cadence

Once or twice per year is sufficient for most users, especially when making dietary or training changes.

Cost

Typical costs

$30–$100 depending on lab, country, and whether additional tests like OGTT or C-peptide are included.

Availability

Where available

Widely available at diagnostic labs and longevity clinics. Fasting insulin and glucose are part of most metabolic panels.

Preparation

How to prepare

Fast for at least 8–12 hours. Avoid coffee, supplements, and intense exercise the evening before for the most consistent results.

Interpretation

Interpreting insulin sensitivity tests helps uncover hidden metabolic issues and can guide precision interventions.
HOMA-IR threshold

Values above 1.8–2.0 suggest early insulin resistance, even if glucose appears normal.

Fasting insulin goal

Longevity-oriented practitioners often aim for fasting insulin below 5 μIU/mL — lower than typical lab references.

Alternatives

Continuous Glucose Monitor (CGM)

Offers real-time glucose tracking and post-meal responses. Doesn’t measure insulin directly but provides rich behavioral data.

Glucose Tolerance Test (OGTT)

Can be done independently but provides best insights when paired with insulin measurements over time.

FAQ

Is fasting insulin better than HbA1c?

They measure different things. Fasting insulin detects issues earlier, while HbA1c reflects long-term glucose exposure. Both are valuable together.

What’s a good HOMA-IR score?

Below 1.8 is ideal for most longevity-focused protocols, though targets may vary by individual factors.