Markers · Metabolic
Fasting insulin in range, beside a glucose that looks normal. Fasting insulin, read against the rest of you.
What Fasting insulin measures, what it does in the body, why it's tested, and the two ranges it's read against. Everything said about the marker here comes from Merlin's own biomarker catalogue.
What Fasting insulin is
Insulin is a pancreatic hormone that regulates blood glucose by facilitating cellular glucose uptake and suppressing hepatic glucose production. Elevated fasting insulin levels often indicate insulin resistance, a precursor to type 2 diabetes, metabolic syndrome, and cardiovascular disease, even when fasting glucose appears normal. Chronically high insulin promotes fat storage, inflammation, and hormonal dysregulation, making it a critical early-warning biomarker for cardiometabolic risk.
What it does in the body
Insulin is secreted by pancreatic beta cells in response to rising blood glucose and amino acids. It promotes glucose uptake in muscle and adipose tissue, inhibits hepatic gluconeogenesis and glycogenolysis, stimulates glycogen and protein synthesis, and inhibits lipolysis. It also plays roles in cellular growth signaling via the PI3K/Akt and MAPK pathways, influencing cell proliferation and survival.
Why it's tested
Fasting insulin is measured to assess insulin resistance and pancreatic beta-cell function, diagnose or risk-stratify prediabetes and type 2 diabetes, evaluate hypoglycemia etiology (e.g., insulinoma), monitor response to lifestyle or pharmacological interventions, and calculate HOMA-IR (Homeostatic Model Assessment of Insulin Resistance) when paired with fasting glucose.
The two ranges
The reference range reflects population statistics. The target reflects physiology.
- Lab reference range
- 2-25 µIU/mL (fasting); laboratory reference ranges may vary slightly
- Functional target
- 2-5 µIU/mL (fasting); under 10 is the functional ceiling
Those are different numbers, and you deserve to know which one you're looking at. Merlin reads your result against both.
Where this lives
A Field Guide to Metabolic Derailment
The field guide that covers Fasting insulin in depth, whole and public.
In a real read
The real read on this site is Cardiovascular, and the metabolic picture is part of how it reads the lipid numbers. In its words, a high particle count "in an insulin-sensitive, low-triglyceride milieu is a categorically different picture than the same count in small dense Pattern B." That's what reading across systems looks like on a real panel.
A real Cardiovascular surface from a real anonymized panel: the score, the narrative, the layers underneath. Yours will be built the same way, on your own numbers.
Educational context for your conversations with your licensed healthcare provider, not a diagnosis or a treatment plan. Merlin reads results; it doesn't diagnose.
Read next to
Bring the panel this number came from. Merlin reads it against everything else you have, every system and every year, then shows you what it means and what's worth finding out next. Start with your first month.
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