Higher levels of inflammatory markers like interleukin (IL)-6 and fibrinogen are associated with greater cognitive decline in older adults with type 2 diabetes, according to a study published in the journal Diabetologia.¹

Researchers from Edinburgh, UK conducted a follow-up study from the Edinburgh Type 2 Diabetes Study to investigate the association between inflammatory markers and any change in cognition in older people with type 2 diabetes over 10 years. “The Edinburgh Type 2 Diabetes Study is a population-based prospective cohort study set up in 2006/2007 of 1066 men and women aged between 60 and 75 years at baseline with type 2 diabetes, living in Edinburgh and the Lothians”.

C-reactive protein, IL-6, tumor necrosis factor-alpha (TNF-α) and fibrinogen were measured for all participants at baseline. Neuropsychological tests to assess major cognitive domains were also carried out at the start of the study. The cognitive tests were repeated after 10 years in 581 participants. Seven individual cognitive tests were used to obtain a general cognitive ability score.

Type 2 diabetes patients with higher baseline fibrinogen and IL-6 levels had greater decrease in  general cognitive ability after adjustment for age, sex and baseline general cognitive ability. But this association lost its significance after adjusting for vascular and diabetes-related factors. But when individual cognitive tests were examined, raised fibrinogen and CRP levels were associated with greater reduction in processing speed, whereas higher IL-6 was associated with greater decrease in tests of executive function and abstract reasoning. These associations between individual cognitive tests and inflammatory markers remained statistically significant even after adjustment for the diabetes- and vascular-related risk factors.

Evidence suggests that type 2 diabetes is an inflammatory disease and is associated with low-grade inflammation. Higher baseline systemic inflammatory markers were associated with greater decline in cognitive abilities in older adults with type 2 diabetes in this 10-year follow-up study, which was independent of vascular and diabetes-related risk factors thus suggesting a potential role of inflammation in cognitive dysfunction over the course of time. These findings may help to identify at-risk groups and chalk out a treatment plan accordingly as also suggested by the study authors, who write that “efforts taken to reduce overall systemic inflammation may be beneficial in preventing the onset and severity of cognitive decline in people with type 2 diabetes”.

Reference

1. Sluiman AJ, et al. Higher baseline inflammatory marker levels predict greater cognitive decline in older people with type 2 diabetes: year 10 follow-up of the Edinburgh Type 2 Diabetes Study. Diabetologia. 2022 Mar;65(3):467-476. doi: 10.1007/s00125-021-05634-w.