The effects of prediabetes and type 2 diabetes mellitus on cognitive status, physical function, and fatigue in older adults: a case-control study

Abstract Objective The purpose of this study was to compare the cognitive status, physical function, and fatigue levels of Type-2 Diabetes Mellitus (T2DM), prediabetes, and healthy older adults. Methods Volunteers aged 60 and over were included in the study. Participants divided into four groups according to hemoglobin A1c (HbA1c) levels: healthy, prediabetes, controlled T2DM, and uncontrolled T2DM. Cognitive function, spatial ability, functional mobility with and without dual-task conditions, reaction time, fatigue, and biochemical parameters were evaluated. Results A total of 94 participants (53 female, 41 male, mean age:67.12±5.84 years) were included. Significant group differences were observed in attention and delayed recall subdomains and total Montreal Cognitive Assesment scores (p<0.05). Additionally, significant differences were found in functional mobility, dual-task performance, foot reaction time, and fatigue levels (all p<0.05). Older adults with uncontrolled T2DM showed poorer cognitive and motor performance than healthy older adults. Adjusted analyses demonstrated that cognitive performance, reaction time, and fatigue-related differences remained significant after controlling for potential confounders, whereas functional mobility-related outcomes were attenuated. Among the biochemical markers, fasting blood glucose levels showed a significant difference among the groups ( p <0.001). Conclusions Uncontrolled T2DM in older adults is associated with impairments in attention, memory, mobility, and motor performance, while fatigue was increased across prediabetic and diabetic individuals. These findings highlight the multidimensional functional impact of dysglycemia in older adults.