The Problem with High Cutoff Values

Current research shows that there are no globally agreed levels for Insulin Resistance and most studies use cutoffs between 1.85-3.0, for HOMA-IR to define insulin resistance since it is a widespread problem, if it is in the wrong direction action needs to be taken and 1.9 to 2.0 is considered a good figure to work with. Here are four countries values.
Spain: 1.85-2.07 (70th-75th percentile)
Turky: 2.46 (HOMA1-IR)
Iran: ~2.8
Some studies use 3.0 (95th percentile)
But more sensitive thresholds exist:

Recent Qatar study (2025) found optimal cutoff at 1.878
Some researchers recommend the 75th percentile (around 2.0)
Others suggest even 50th percentile might be more appropriate.

Why This Matters for the Hypertension Study

If the 2009 hypertension study you referenced used a high cutoff (likely 3.0 or higher based on standards at that time), then:

Only 50% were classified as insulin resistant using that conservative threshold
But if a lower, more sensitive cutoff (like 1.85-2.0) had been used, the percentage would be significantly higher

Estimation of 75-90% is very reasonable because:
Studies using lower cutoffs (around 2.0) find insulin resistance prevalence of 51-65% in general populations
In hypertensive populations specifically, the rate would be even higher
Modern understanding suggests insulin resistance exists on a spectrum, starting well before traditional cutoffs.

The Conservative Bias Problem
Research has consistently used overly conservative thresholds because:
They were based on the 95th percentile of “healthy” populations
But many in those “healthy” populations already had early insulin resistance
This creates a circular problem: defining normal based on an already-unhealthy population
Using more appropriate cutoffs would reveal that the vast majority of people with essential hypertension have insulin resistance as a primary driver, not just 50%.