Factors associated with cognitive impairment in patients with newly diagnosed type 2 diabetes: a cross-sectional study

Abstract

Objectives: Type 2 diabetes (T2DM) is strongly associated with cognitive impairment but the factors within T2DM that predispose to cognitive impairment are less well understood, while previous studies have investigated samples with T2DM of widely varying duration. We aimed to investigate the factors associated with cognitive impairment in patients with newly diagnosed T2DM.

Method: In a multi-ethnic sample with T2DM diagnosed in the last 6 months, we assessed cognitive function using the 13-item modified telephone interview for cognitive status (TICS-M). Cognitive function was assessed both categorically (impairment defined as lowest 10% of scores with the remainder as controls) and as continuous TICS-M score. Its associations were tested in univariate and multivariate analyses with a range of biological, psychological and sociodemographic factors.

Results: Of 1790 participants, 1680 had a complete TICS-M assessment at baseline. After controlling for covariates, older age (p < 0.001) and lower verbal intelligence (p < 0.001) were associated with both cognitive impairment and lower TICS-M scores, while non-white ethnicity (p < 0.001), female gender (p = 0.02) and higher HbA1c (p = 0.002) were associated with lower TICS-M scores. Depression (defined as Patient Health Questionnaire-9 score ≥10), elevated inflammatory markers and body mass index were not associated with cognitive function after controlling for covariates.

Conclusion: Age, verbal intelligence, female gender and HbA1c are associated with cognitive performance in T2DM soon after diagnosis. Previously reported associations with depression and inflammatory markers may occur later as causes or consequences of T2DM. Longitudinal analyses are needed to assess potentially modifiable factors predicting cognitive decline in early T2DM.

Keywords:

• diabetes
• cognitive impairment
• glycaemic control
• ethnicity
• verbal intelligence

Acknowledgements

The authors would like to thank the patients who volunteered to participate in this study; the SOUL-D research team, King's College London, London, UK (J. Schonbeck, J. Valka, N. Iles, B. Jackson, E. Britneff, L. East, J. Hunt, S. Mann, G. Knight, L. Marwood, R. Stopford, K. Twist and A. Bayley); the staff at participating general practices; the Primary Care Research Network (PCRN-GL) for their assistance in recruiting the general practices; the Diabetes Research Network and the South London Comprehensive Local Research network.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This paper presents independent research supported by funding from the National Institute of Heath Research (NIHR) under its Programme Grants for Applied Research Programme [grant RP-PG-0606-1142]. The views expressed in this publication are those of the authors and not necessarily those of the NHS, the NIHR or the Department of Health.