Relationship between glycated hemoglobin A1c and cognitive function in nondemented elderly patients with type 2 diabetes

Elderly patients with type 2 diabetes are at a greater risk for cognitive decline. The purpose of this study was to assess the relationship between the degree of hyperglycemia and cognitive status in nondemented, elderly diabetics. Between Jan 2013 and Dec 2014, 1174 geriatric patients with type 2 diabetes were enrolled in the study (579 males; age ≥ 60 years; from Fuzhou, Fujian, China). Cognitive function was measured with the Mini Mental State Examination (MMSE) and Montreal Cognitive Assessment (MoCA). A statistically significant, age-adjusted association was observed between the A1C levels and the scores on two cognitive tests (MMSE and MoCA). Specifically, a 1% higher A1C value was associated with a 0.21-point lower MMSE score (95% CI; compare -0.11 to -0.28; P < 0.0001), as well as a 0.11-point lower MoCA score (95% CI; compare -0.10 to -0.38; P < 0.0001). Higher A1C levels were not significantly associated with lower MMSE and MoCA test scores after adjusting for all variables. No significant correlation was found between the two variables in patients older than 80 years of age (n = 215; OR = 1.019; 95% CI = 0.968 - 1.099; p = 0.251). Evidence strongly suggests that chronic hyperglycemia is associated with a decline in cognitive function in nondemented elderly patients with type 2 diabetes. When cognitive assessments are made, comprehensive factors such as advanced age, education level, duration of diabetes, hypertension and other vascular risks should be taken into account. For older geriatric patients (age ≥ 80 years), there is no significant correlation between A1c levels and cognitive function.