Cohort studyindependent cross-checkabstract checked I-SRC-128 standard review

Insulin sensitivity falls years before diabetes

Trajectories of glycaemia, insulin sensitivity, and insulin secretion before diagnosis of type 2 diabetes: an analysis from the Whitehall II study.

Overview

Tabák AG et al.. Lancet 2009 · PMID 19515410 · DOI 10.1016/S0140-6736(09)60619-X

In 6538 British adults, those who later got diabetes showed falling insulin sensitivity in the 5 years before diagnosis.

Does the study support the specific claim? No · Methodological quality: high

Study explained simply

What did the researchers want to find out?: Track metabolism before diabetes
How was the study done?: Cohort
How many people, animals or samples were studied?: 6538 adults
What was actually found?: Insulin sensitivity fell before diagnosis
How large was the observed effect?: HOMA-S to 86.7%
What do the results mean in everyday life?: Insulin resistance is a measurable early warning sign
What are the study's limitations?: HOMA not clamp
What does it say about Elawady's specific claim?: Contradicts denial
Do the results apply to Germany and Europe?: High

Authors: Tabák AG et al.
Journal: Lancet
Year: 2009
Identifier: PMID 19515410 DOI 10.1016/S0140-6736(09)60619-X
Verification: verified – PubMed efetch 2026-10-26; Crossref works record checked
Retracted: no
Corrections: none
Extent checked: abstract only
Conflicts of interest and funding: No conflicts declared; public funders.

How do glucose, insulin sensitivity and insulin secretion change in the years before diagnosis of type 2 diabetes?

Study design: Cohort study – Prospective occupational cohort (Whitehall II), retrospective trajectory analysis
Population: British civil servants without diabetes at baseline
Country: UK
Period: Median follow-up 9.7 years
Sample size: 6538; 505 incident diabetes cases
Inclusion and exclusion criteria: No diabetes at baseline

Exposure / intervention: Time before diagnosis
Comparator: Non-diabetic participants
Endpoints: Fasting/2-h glucose, HOMA insulin sensitivity, HOMA beta-cell function
Statistical methods: Multilevel models

Results: In those who developed diabetes, HOMA insulin sensitivity decreased steeply during the 5 years before diagnosis (to 86.7%); beta-cell function rose between years 4 and 3 before diagnosis (85.0% to 92.6%) and then fell to 62.4%; fasting glucose rose steeply from 3 years before diagnosis (5.79 to 7.40 mmol/L).
Absolute risks: not applicable
Authors' conclusion: Changes in glucose, insulin sensitivity and secretion occur 3-6 years before diagnosis.

Descriptive trajectories; temporal ordering supports insulin resistance as an early process.

Shows measurable decline in insulin sensitivity before type 2 diabetes in a large population.

UK cohort, applicable.

Strong cohort evidence that insulin resistance exists and precedes diabetes.

Multidimensional assessment
Multidimensional assessment
Authenticity of the source	verified
Methodological quality	high
Risk of bias	low
Precision of results	high
Directness	direct
Reproducibility	replicated
Consistency with the overall evidence	consistent
Regional transferability	high
Adequacy of the interpretation (by the archive)	not applicable