A prospective analysis of elevated fasting glucose levels and cognitive function in older people: results from the PROSPER and Rotterdam studies.

  1. for the PROSPER and Rotterdam studies
  1. 1Department of Epidemiology, Erasmus MC, Rotterdam, the Netherlands
  2. 2Department of Gerontology and Geriatrics, Leiden University Medical Centre, Leiden, the Netherlands
  3. 3Faculty of Medicine, University of Glasgow, Glasgow, Scotland
  4. 4Department of Neurology, Leiden University Medical Centre, Leiden, the Netherlands
  5. 5Department of Internal Medicine, Erasmus MC, Rotterdam, the Netherlands
  6. 6Department of Epidemiology & Public Health, University College Cork, Cork, Ireland.

Abstract

Background: Diabetes mellitus is associated with cognitive impairment in older people. However, the link between elevated fasting glucose levels and insulin resistance in non-diabetics, and the risk of cognitive impairment is unclear.

Objective: To investigate the relation between fasting glucose levels, insulin resistance, and cognitive impairment in old age.

Research Design and Methods: We analyzed data from in total 8447 participants of two independent prospective studies: the PROspective Study of Pravastatin in the Elderly at Risk (PROSPER): 5019 participants, age 69-84 years, and the Rotterdam Study: 3428 participants, age 61-97 years. Fasting glucose levels were assessed at baseline in both studies, fasting insulin levels were assessed in the Rotterdam Study only. Cognitive function was assessed in both studies at baseline and during follow-up.

Results: Subjects with diabetes had impaired cognitive function at baseline. In contrast, in people without a history of diabetes there was no clear association between baseline fasting glucose levels and executive function and memory, nor was there a consistent relation between elevated baseline fasting glucose levels and the rate of cognitive decline in either cohort. Insulin resistance (HOMA index) was also unrelated to cognitive function and decline.

Conclusions: Elevated fasting glucose levels and insulin resistance are not associated with worse cognitive function in older people without a history of diabetes. These data suggest either a threshold for effects of dysglycaemia on cognitive function, or that factors other than hyperglycaemia contribute to cognitive impairment in individuals with frank diabetes.

Footnotes

    • Received April 21, 2009.
    • Accepted March 25, 2010.

This Article

  1. Diabetes
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