Higher glycated hemoglobin amplifies the effect of apolipoprotein E epsilon 4-related cognition and olfaction impairments in type 2 diabetes

Figure 1 Study profile. Apolipoprotein E genotype and glycated hemoglobin level in peripheral blood samples were assessed from 636 patients with type 2 diabetes mellitus. Cognitive and olfactory functions, primarily mediated by the temporal lobe (dashed-line box), were evaluated using the mini-mental state examination and the Connecticut chemosensory clinical research center test, respectively. T2DM: Type 2 diabetes mellitus; HbA1c: Glycated hemoglobin; APOE: Apolipoprotein E.

Figure 2 Effects of apolipoprotein E epsilon 4 genotype on cognitive and olfactory function. A: Apolipoprotein E epsilon 4 (APOE4) carriers had significantly lower mini-mental state examination scores compared to non-APOE4 carriers (P = 0.0424); B: APOE4 carriers had significantly lower olfactory threshold scores compared to non-APOE4 carriers (P = 0.0383). APOE4 - represents non-APOE4 carriers, APOE4 + represents APOE4 carriers. APOE4: Apolipoprotein E epsilon 4; MMSE: Mini-mental state examination.

Figure 3 Effects of apolipoprotein E epsilon 4 genotype and glycated hemoglobin level on cognitive and olfactory function. A: Mini-mental state examination scores were significantly lower in the apolipoprotein E epsilon 4 (APOE4) + with high glycated hemoglobin (HbA1c) group compared to the APOE4 - with high HbA1c group (P = 0.0277); B: Olfactory threshold score was significantly lower in the APOE4 + with high HbA1c group compared to the APOE4 - with high HbA1c group (P = 0.017). HbA1c: Glycated hemoglobin; APOE4: Apolipoprotein E epsilon 4; MMSE: Mini-mental state examination.