Glycemic Control is Related to Cognitive Dysfunction in Elderly People with Type 2 Diabetes Mellitus in a Rural Chinese Population

Abstract

Background: There is an increasing interest on Cognitive Impairment (CI) in patients with type 2 diabetes mellitus (T2DM), but evidence is conflicting regarding the association between CI and glycemic control.

Objective: The present study aimed to estimate the prevalence of CI in patients with T2DM from northern rural China in order to determine whether cognitive dysfunction is related to glycemic control.

Methods: First, we conducted a study with a cross-sectional design. We performed cluster random sampling of 1848 residents who were aged 60 years or older and lived in the countryside in China. All eligible participants with and without T2DM were interviewed and screened for cognitive function status. Diagnoses for dementia and Cognitive Impairment No Dementia (CIND) were based on the standard criteria. Second, on the basis of the results of the cross-sectional survey, we conducted a case-control study. In the T2DM group, we identified cases of T2DM with Cognitive Impairment (T2DM-CI), as well as cases of T2DM with normal cognition (T2DM-NC) to be used as controls. The effects of specific diabetes-related variables were examined. After matching for sex, age, and education level in the T2DM-CI and T2DM-NC groups, multivariate logistic regression analyses were performed to evaluate risk factors for T2DM-CI.

Results: In the cross-sectional study, the prevalence of T2DM with CIND and dementia were 28.3% (95% CI: 23.5-33.2) and 9.5% (95% CI: 6.3-12.6), respectively. Compared with subjects without DM, the prevalence of CI in T2DM patients was more frequent than the prevalence of CI in the general population in almost every age group. In the case-control study, the multivariate logistic regression analyses showed that variables, including duration from diabetes onset, glycosylated hemoglobin A1c level (HbA1c), and severe hypoglycemia history, were significantly associated with an increased risk of CI in patients with T2DM (odds ratios [ORs] [95%CIs]: 1.67 [1.03-2.70], 1.40 [1.15-1.72], and 2.72 [1.02- 7.21], respectively [P <0.05]).

Conclusion: The present study demonstrates a high prevalence of CI in patients with T2DM among the elderly population of rural China. Glycemic control, including HbA1c and exposure to severe hypoglycemia, affected cognitive function in patients with T2DM.

Keywords: Cognitive impairment; HbA1c; dementia; hypoglycemia; rural China; type 2 diabetes mellitus (T2DM)..