Diabetes and cortical thickness in ethnically diverse cognitively normal older adults.

INTRODUCTION

Mechanisms linking type 2 diabetes mellitus (T2DM) with dementia are poorly understood. We examined T2DM associations with cortical thickness and hippocampal volume in ethnoracially diverse, cognitively unimpaired older adults.

METHODS

In 2171 cognitively unimpaired older adults, we examined (1) how T2DM related to cortical thickness and hippocampal volume, (2) whether associations were independent of socioeconomic factors and comorbidities, (3) whether associations were driven by hyperglycemia or hyperinsulinemia, and (4) how associations varied by self-reported race/ethnicity.

RESULTS

T2DM was correlated with thinner cortex independent of socioeconomic factors and comorbidities, and this was driven by higher hemoglobin A1c (HbA1c). Higher HbA1c levels were correlated with thinner cortex in diabetics and non-diabetics. T2DM-cortical thickness associations were strong and widespread in Hispanic participants, modest and limited to temporal regions in non-Hispanic White participants, and not present in non-Hispanic Black adults.

DISCUSSION

T2DM is associated with a thinner cortex, and this is driven by poor glycemic control.

HIGHLIGHTS

T2DM is associated with a thinner cortex.The T2DM-cortical thickness relationship is likely driven by poor glucose control.Higher HbA1c levels correlated with thinner cortex in diabetics and non-diabetics.The T2DM-cortical thickness association varied by self-reported ethnicity/race.