Longevity & Aging · Metabolic & Cardiometabolic
dynamic insulin testing OGTT-with-insulin CGM fasting insulin detects insulin resistance years before fasting glucose or HbA1c become abnormal
In plain terms: Can measuring insulin catch metabolic trouble years before a standard glucose test does?
Yes — longitudinal cohorts show insulin resistance and compensatory hyperinsulinemia develop years before fasting glucose/HbA1c cross into abnormal, so insulin-based measures flag dysfunction earlier.
Evidence ladder
How far up the ladder this claim has climbed. A high consensus on a low rung means "consistent so far," not "proven in people."
Top evidence so far: Population patterns (Observational)
How the studies fall
The evidence (4)
| Source | Grade | Stance | Quality | Finding |
|---|---|---|---|---|
| Rawlings 2017 · Diabetes Care | observational | mixed | moderate | ARIC: glucose peaks/HbA1c do predict long-term dementia/decline — showing glucose markers carry real signal too, so insulin testing is earlier but glucose is not uninformative. |
| Tabak 2009 · Lancet | observational | supports | high | Whitehall II: in those developing T2DM, insulin sensitivity fell and compensatory hyperinsulinemia rose 3-5+ years before diagnosis, with fasting glucose staying near-normal until a late steep rise. |
| Faerch 2013 · Lancet Diabetes Endocrinol | observational | supports | high | Whitehall II subtype analysis: distinct pre-diagnosis trajectories of insulin sensitivity/secretion, confirming metabolic dysfunction is detectable well before glucose-based diagnosis. |
| Hulman 2017 · Diabetologia | observational | supports | moderate | Trajectory modeling shows insulin-sensitivity/secretion changes precede diabetes and differ by ethnicity — earliest divergence is in insulin dynamics, not fasting glucose. |
Disagree, or know a study we missed?
We grade by evidence, not opinions. The way to weigh in is to point us to a study we haven't cited (check the evidence table above first), or to flag a problem with one we have. Every submission is reviewed; if it holds up, the grade updates and shows in Science Changes Its Mind.
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Educational only, not medical advice. Grades and scores reflect published evidence weighted by study design and quality; see the methodology.