Diabetes, glucose control, and 9-year cognitive decline among older adults without dementia.
OBJECTIVE
To determine if prevalent and incident diabetes mellitus (DM) increase risk of cognitive decline and if, among elderly adults with DM, poor glucose control is related to worse cognitive performance. DESIGN Prospective cohort study.


METHODS
Health, Aging, and Body Composition Study at 2 community clinics.


METHODS
A total of 3069 elderly adults (mean age, 74.2 years; 42% black; 52% female).


METHODS
Participants completed the Modified Mini-Mental State Examination (3MS) and Digit Symbol Substitution Test (DSST) at baseline and selected intervals over 10 years. Diabetes mellitus status was determined at baseline and during follow-up visits. Glycosylated hemoglobin A1c level was measured at years 1 (baseline), 4, 6, and 10 from fasting whole blood.


RESULTS
At baseline, 717 participants (23.4%) had prevalent DM and 2352 (76.6%) were without DM, 159 of whom developed incident DM during follow-up. Participants with prevalent DM had lower baseline test scores than participants without DM (3MS: 88.8 vs 90.9; DSST: 32.5 vs 36.3, respectively; t = 6.09; P = .001 for both tests). Results from mixed-effects models showed a similar pattern for 9-year decline (3MS: -6.0- vs -4.5-point decline; t = 2.66; P = .008; DSST: -7.9- vs -5.7-point decline; t = 3.69; P = .001, respectively). Participants with incident DM tended to have baseline and 9-year decline scores between the other 2 groups but were not statistically different from the group without DM. Multivariate adjustment for demographics and medical comorbidities produced similar results. Among participants with prevalent DM, glycosylated hemoglobin A1c level was associated with lower average mean cognitive scores (3MS: F = 8.2; P for overall = .003; DSST: F = 3.4; P for overall = .04), even after multivariate adjustment.


CONCLUSIONS
Among well-functioning older adults, DM and poor glucose control among those with DM are associated with worse cognitive function and greater decline. This suggests that severity of DM may contribute to accelerated cognitive aging.
Departments of Psychiatry, University of California, San Francisco, and San Francisco, VA, USA. kristine.yaffe@ucsf.edu
Kristine
K
Yaffe
Cherie
C
Falvey
Nathan
N
Hamilton
Ann V
AV
Schwartz
Eleanor M
EM
Simonsick
Suzanne
S
Satterfield
Jane A
JA
Cauley
Caterina
C
Rosano
Lenore J
LJ
Launer
Elsa S
ES
Strotmeyer
Tamara B
TB
Harris
D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000523:psychology*; D001786:Blood Glucose; D003071:Cognition; D003072:Cognition Disorders / Q000209:etiology* / Q000523:psychology; D003922:Diabetes Mellitus, Type 1 / Q000150:complications* / Q000523:psychology; D003924:Diabetes Mellitus, Type 2 / Q000150:complications* / Q000523:psychology; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D009483:Neuropsychological Tests; D011446:Prospective Studies; D012306:Risk; D057566:Self Report
D001786:Blood Glucose