Fasting Insulin · low result
What does a low Fasting Insulin mean?
Short answer
Low fasting insulin is normal in lean, insulin-sensitive people and after prolonged fasting. In someone with high glucose, a low insulin suggests the pancreas isn't producing enough — type 1 diabetes, late-stage type 2, pancreatic disease — and C-peptide helps confirm. On its own, with a normal glucose, it's reassuring rather than concerning.
Medically reviewed by Youmna DiStefano, MD · Last reviewed September 2026
What is the normal range for Fasting Insulin?
- age 18+, fasting: 2.00 – 20.0 uIU/mL
Full reference table, citations and testing options: Fasting Insulin biomarker page.
What are the common causes of low Fasting Insulin?
- Normal insulin sensitivity
- Prolonged fasting
- Type 1 diabetes or advanced type 2 (with high glucose)
- Pancreatic disease
- Insulin degradation in a delayed sample
What symptoms go with low Fasting Insulin?
- None with normal glucose
- Thirst, urination, weight loss if glucose is high
How do you recheck Fasting Insulin?
Prices are cash-pay; every order adds one $6 lab processing fee. Physician authorization is included; no insurance or referral needed.
| Test or panel | Type | Price | Fasting | Results |
|---|---|---|---|---|
| Diabetes Screening Panel | Panel · 3 tests | $59.99 | Yes | 2–5 business days |
| Pre-Diabetes Panel | Panel · 5 tests | $89.99 | Yes | 2–5 business days |
| Metabolism & Weight Loss Panel | Panel · 8 tests | $119.99 | Yes | 2–5 business days |
| Insulin, Fasting | Test | $22.99 | Yes | 2–4 business days |
Common questions
Is a fasting insulin of 3 too low?
With a normal glucose, no — it indicates good insulin sensitivity. With a high glucose, it raises the question of insulin deficiency.
Sources
Educational content, not a diagnosis. Lab results are one input; a clinician interprets them with your history and exam.