October 10, 2018Open Access
Fasting Glucose Variability in Young Adulthood and Cognitive Function in Middle Age: The Coronary Artery Risk Development in Young Adults (CARDIA) Study
Key Result
A 1-SD increment in fasting glucose variability during young adulthood was associated with worse cognitive scores at year 25, including DSST (coefficient -0.95; 95% CI -1.54 to -0.36).
Study Design
Type
Cohort (n=3,307)
Structured PICO
Is higher intraindividual fasting glucose variability in young adulthood associated with worse cognitive function in middle age?
P
Population
3,307 young adults aged 18-30 years at baseline, followed for 25 to 30 years to assess the association between fasting glucose variability and cognitive function in midlife.
E
Exposure
Higher intraindividual variability in fasting glucose (FG) below the threshold of diabetes (measured by coefficient of variation [CV-FG] and average real variability [ARV-FG])
C
Comparator
Lower intraindividual fasting glucose variability
O
Outcome
Cognitive function at years 25 and 30 assessed via Digit Symbol Substitution Test (DSST), Rey-Auditory Verbal Learning Test (RAVLT), Stroop Test, Montreal Cognitive Assessment, and category and letter fluency testssurrogate
Higher fasting glucose variability during young adulthood, even below the diabetes threshold, is associated with worse cognitive function in midlife independent of absolute fasting glucose levels.
Main Result
Effect estimate: standardized regression coefficient -0.95 (95% CI -1.54, -0.36)
Abstract
OBJECTIVE: To determine whether intraindividual variability in fasting glucose (FG) below the threshold of diabetes is associated with cognitive function in middle adulthood beyond increasing FG. RESEARCH DESIGN AND METHODS: We studied 3,307 CARDIA (Coronary Artery Risk Development in Young Adults) Study participants (age range 18-30 years and enrolled in 1985-1986) at baseline and calculated two measures of long-term glucose variability: the coefficient of variation about the mean FG (CV-FG) and the absolute difference between successive FG measurements (average real variability ARV-FG) before the onset of diabetes over 25 and 30 years of follow-up. Cognitive function was assessed at years 25 (2010-2011) and 30 (2015-2016) with the Digit Symbol Substitution Test (DSST), Rey-Auditory Verbal Learning Test (RAVLT), Stroop Test, Montreal Cognitive Assessment, and category and letter fluency tests. We estimated the association between glucose variability and cognitive function test score with adjustment for clinical and behavioral risk factors, mean FG level, change in FG level, and diabetes development, medication use, and duration. RESULTS: After multivariable adjustment, 1-SD increment of CV-FG was associated with worse cognitive scores at year 25: DSST, standardized regression coefficient -0.95 (95% CI -1.54, -0.36); RAVLT, -0.14 (95% CI -0.27, -0.02); and Stroop Test, 0.49 (95% CI 0.04, 0.94). Findings were similar between CV-FG with each cognitive test score at year 30 and when we used an alternative measure of variability (ARV-FG) that captures variability in successive FG values. CONCLUSIONS: Higher intraindividual FG variability during young adulthood below the threshold of diabetes was associated with worse processing speed, memory, and language fluency in midlife independent of FG levels.