Cognition in the Early Stage of Type 2 Diabetes
Carla Ruis , MSC , 1 ,
Geert Jan Biessels , PHD 1 ,
Kees J. Gorter , PHD 2 ,
Maureen van den Donk , PHD 2 ,
L. Jaap Kappelle , PHD 1 and
Guy E.H.M. Rutten , PHD 2
1 Department of Neurology, Rudolf Magnus Institute of Neuroscience, University Medical Center Utrecht, the Netherlands;
2 Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, the Netherlands.
Corresponding author: Carla Ruis, c.ruis{at}umcutrecht.nl .
Abstract
OBJECTIVE Type 2 diabetes is known to be associated with decrements in memory and executive functions and information-processing speed.
It is less clear, however, at which stage of diabetes these cognitive decrements develop and how they progress over time.
In this study, we investigated cognitive functioning of patients with recent screen-detected type 2 diabetes, thus providing
insight into the nature and severity of cognitive decrements in the early stage of the disease. Possible risk factors were
also addressed.
RESEARCH DESIGN AND METHODS Included in this study were 183 diabetic patients from a previously established study cohort and 69 control subjects. A full
neuropsychological assessment, addressing six cognitive domains, was made for each participant. Raw test scores were standardized
into z scores per domain and compared between the groups. Possible risk factors for cognitive decrements were examined with multivariate
linear regression.
RESULTS Relative to scores for the control group, mean z scores were between 0.01 and 0.2 lower in the diabetic group across all
domains, but after adjustment for differences in IQ between patients and control subjects, only memory performance was significantly
reduced (mean difference −0.15 [95% CI −0.28 to −0.03]). A history of macrovascular disease and current smoking were significant
determinants of slower information-processing speed in patients with diabetes.
CONCLUSIONS This study shows that modest cognitive decrements are already present at the early stage of type 2 diabetes. A history of
macrovascular disease and smoking are significant risk factors for some early decrements.
Footnotes
The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore
be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
Received December 8, 2008.
Accepted March 25, 2009.
Readers may use this article as long as the work is properly cited, the use is educational and not for profit, and the work
is not altered. See http://creativecommons.org/licenses/by-nc-nd/3.0/ for details.
© 2009 by the American Diabetes Association....

Cognition in the Early Stage of Type 2 Diabetes

10.2337/dc08-2143