The Association of Late-Life Diabetes Status and Hyperglycemia With Incident Mild Cognitive Impairment and Dementia: The ARIC Study.

Objective: We sought to examine associations in older adults among diabetes, glycemic control, diabetes duration, and biomarkers of hyperglycemia with incident mild cognitive impairment (MCI) and incident dementia.
Research Design and Methods: We conducted a prospective analysis of 5,099 participants from the Atherosclerosis Risk in Communities (ARIC) Study who attended the fifth (2011-2013) exam. Cognitive status was assessed during follow-up via telephone calls, death certificate codes, surveillance, and a follow-up examination (2016-2017). We defined incident cognitive impairment as incident MCI or incident dementia in persons dementia-free at the index examination; we also examined each outcome separately. Diabetes was defined using self-report, medications, or HbA _1c ≥6.5%; poor glycemic control in persons with diabetes was defined as HbA _1c ≥7%. We examined the following biomarkers of hyperglycemia: HbA _1c , fructosamine, glycated albumin, and 1,5-anhydroglucitol.
Results: Mean age at baseline was 76 years, 59% were female, and 21% were black. Diabetes (hazard ratio [HR] 1.14 [95% CI 1.00, 1.31]), poor glycemic control in persons with diabetes (HR 1.31 [95% CI 1.05, 1.63]), and longer diabetes duration (≥5 vs. <5 years; HR 1.59 [95% CI 1.23, 2.07]) were significantly associated with incident cognitive impairment. We found a J-shaped association between HbA _1c and incident dementia. Glycated albumin and fructosamine were also associated with incident dementia, independently of HbA _1c . HbA _1c and fructosamine were also associated with incident MCI.
Conclusions: Diabetes status, poor glycemic control, and longer diabetes duration were associated with worse cognitive outcomes over a median follow-up of 5 years.
(© 2019 by the American Diabetes Association.)