09/07/2026
D’où l’importance de mesurer glycémie, insuline et HOMA test qui permet de détecter des années avant un potentiel état pré diabétique. Et oui, le diabète ne vient pas du jour au lendemain, et il existe bien un état pré diabétique!
A normal fasting glucose gets read as an all-clear for metabolic health. It is the last thing to break, not the first.
In the Whitehall II study (Tabák et al., Lancet 2009), 6,538 adults without diabetes were examined every few years, and the trajectories of those who went on to develop type 2 diabetes were reconstructed up to 13 years before diagnosis. The order of events is the story. Insulin sensitivity fell steeply over the five years before diagnosis. Fasting glucose stayed flat and only began its sharp climb about three years out, rising from 5.79 to 7.40 mmol/L. Beta-cell function actually rose first, the pancreas compensating, then collapsed as diagnosis approached.
Glucose looks normal for years because insulin is quietly doing overtime to keep it there. As tissues resist insulin, the pancreas secretes more to hold the line. Fasting glucose is a lagging indicator: it only rises once beta cells can no longer keep up. Fasting insulin, or HOMA-IR, captures the compensation phase a glucose test misses entirely. By the time glucose crosses the diabetic threshold, the machinery has been straining for years.
Whitehall II was 71% male and 91% white, an occupational cohort, and the pattern can move faster in other populations; the companion South Asian analysis showed exactly that. It is observational: it maps the natural history, not proof that measuring insulin earlier changes anything. Fasting insulin assays are not standardized, part of why it is not a routine test, and HOMA-IR is a surrogate, not a gold-standard clamp.
What the evidence supports: insulin resistance is measurable years before fasting glucose moves, so a normal glucose says little about the insulin behind it, and fasting insulin opens a much longer runway to catch dysglycemia early. What it does not support: that fasting insulin is a validated screening test with agreed cutoffs, or that acting on it sooner improves hard outcomes. The open question is whether routine fasting-insulin screening plus early intervention lowers diabetes incidence. That trial has not been run.
Tabák et al., Lancet 2009
