I don't see one comment criticizing the study, below is the study design and below this section is much more information about how they generate the quotable number. It looks like at its core there are separate data sources which de-link the person with T2D to their specific diet features (I might be way off base here so please correct if I'm wrong). Instead they are doing quite some complicated fitting to deduce these numbers. I'm not an expert in this field, and even the field I am this type of statistical work would too much for me to easily understand, but I will say this: there is a lot of lost information and to me its difficult to know whether I should base dietary decisions on this. Anyway I do not need to be told processed meat is bad for me, it destroys my gut every time I eat it and still I go back for more.
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Study design
A comparative risk assessment model55 estimated the numbers, proportions and uncertainty of global T2D cases attributable to suboptimal intake of key dietary factors (Extended Data Fig. 1). Comparative risk assessment does not use ecologic correlations to estimate risk but incorporates independently derived inputs and parameters on demographics, risk factors, their etiologic effects and disease incidence to model attributable burdens55. For this investigation, we leveraged input data and corresponding uncertainty in 184 countries on (1) population dietary intake distributions based on individual-level survey data from the GDD (http://www.globaldietarydatabase.org/)56; (2) population overweight (BMI ≥ 25 kg m−2) and underweight (BMI https://www.nature.com/articles/s41591-023-02278-8
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