Actually, that 2020 report[0] does mention diabetes:

>Overall, a growing body of evidence supports the nine potentially modifiable risk factors for dementia modelled by the 2017 Lancet Commission on dementia prevention, intervention, and care: less education, hypertension, hearing impairment, smoking, obesity, depression, physical inactivity, diabetes, and low social contact.

[0] Full report from July 2020 issue of The Lancet: https://www.thelancet.com/journals/lancet/article/PIIS0140-6...