Impact of blood glucose on cognitive function in insulin resistance: novel insights from ambulatory assessment

BACKGROUND/OBJECTIVES: Insulin resistance (IR)-related disorders and cognitive impairment lead to reduced quality of life and cause a significant strain on individuals and the public health system. Thus, we investigated the effects of insulin resistance (IR), and
blood glucose fluctuations on cognitive function under laboratory and free-living conditions, using ecological momentary assessment (EMA).
SUBJECTS/METHODS: Baseline assessments included neuropsychological tests and blood analysis. Individuals were classified as either insulin-sensitive (<2) or insulin-resistant (≥2), based on their Homeostatic Model Assessment (HOMA-IR) values. Continuous glucose monitoring (CGM) using a percutaneous sensor was performed for 1 week. Using multiple linear regression, we examined the effects of HOMA-IR and CGM metrics on cognitive domains. Working memory (WM) performance, which was assessed using EMA, 4 times a day for 3 consecutive days, was matched to short-term pre-task CGM metrics. Multilevel analysis was used to map the within-day associations of HOMA-IR, short-term CGM metrics, and WM.
RESULTS: Analyses included 110 individuals (mean age 48.7 ± 14.3 years, 59% female, n = 53 insulin-resistant). ... mehrIR was associated with lower global cognitive function (b = −0.267, P = 0.027), and WM (b = −0.316; P = 0.029), but not with executive function (b = −0.216; P = 0.154) during baseline. EMA showed that higher HOMA-IR was associated with lower within-day WM performance (β = −0.20, 95% CI −0.40 to −0.00). CGM metrics were not associated with cognitive performance.
CONCLUSIONS: The results confirm the association between IR and decrements in global cognitive functioning and WM, while no effects of CGM metrics were observed, making IR a crucial time point for intervention. Targeting underlying mechanisms (e.g., inflammation) in addition to glycemia could be promising to minimize adverse cognitive effects.