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Memory Impairments Associated With Postprandial Hyperglycemia and Glycemic Control

Comment on Greenwood et al.

¹ Research Institute of the Diabetes Academy, Diabetes Center Mergentheim, Bad Mergen-theim, Germany
² Department of Neuropsychology, Rehabilitation Clinic Staffelstein, Bad Staffelstein, Germany
³ Diabetes Clinic, Diabetes Center Mergentheim, Mergentheim, Germany

Address correspondence to Dr. Thomas Kubiak, PhD, Forschungsinstitut der Diabetes Akademie Mergentheim (FIDAM), Diabetes Zentrum Mergentheim, Th.-Klotzbuecher-Str. 12, D-97980 Bad Mergentheim, Germany. E-mail: kubiak{at}diabetes-zentrum.de

It was with interest that we read the study by Greenwood et al. (1), which investigated the impact of postprandial hyperglycemia on memory function in type 2 diabetic patients and demonstrated impaired memory function after carbohydrate ingestion. As they thoroughly discussed, the impact of glycemic control and transient hyperglycemia has been under investigation since the mid-1980s (2,3), with study results that are heterogeneous and not very conclusive. In fact, data from a study at our diabetes center (4) comprising 53 type 2 diabetic patients suggest that glycemic control has no influence on cognitive functioning, including memory (Auditory Verbal Learning Test), whereas patients with diabetic complications show lower performance.

One reason for the heterogeneity of results probably stems from the lack of consensus on which instruments to use for cognitive function assessment (5) and the usually small sample sizes. In this respect, unfortunately, Greenwood et al. did not use the standard versions of the tests for memory assessment but instead used instruments that were constructed of parallel forms and had obviously undergone profound changes, like omitting items. The precise nature of the test that was applied is not described in their previous study either (6). Although they thoroughly addressed parallels of the versions used, the possible interference effects of several verbal memory tests used in a row are not discussed.

Taken together with the small sample size, the large interindividual variability of performance within the groups, and hence the fact that the adequacy of regression analysis is disputable, in our point of view the conclusions of Greenwood et al. are daring. Surely, neuropsychological effects of transient hyperglycemic excursions are worth being studied further, but concluding that ingestion of one-half bagel and grape juice leads to acute memory impairment seems, in our opinion, too far-reaching.

References

1. Greenwood CE, Kaplan RJ, Hebblethwaite S, Jenkins DJA: Carbohydrate-induced memory impairment in adults with type 2 diabetes. Diabetes Care 26:1961–1966, 2003[Abstract/Free Full Text]
   
2. Holmes CS: Metabolic control and auditory information processing at altered glucose levels in insulin-dependent diabetes. Brain Cogn 6:161–174, 1987[Medline]
   
3. Holmes CS: Neuropsychological and Behavioral Aspects of Diabetes. New York, Springer, 1990
   
4. Hewer W, Mussell M, Rist F, Kulzer B, Bergis K: Short-term effects of improved glycemic control on cognitive function in patients with type 2 diabetes. Gerontology 49:86–92, 2003[Medline]
   
5. Strachan MW, Frier BM, Deary IJ: Cognitive assessment in diabetes: the need for consensus (Editorial). Diabet Med 14:421–422, 1997[Medline]
   
6. Kaplan RJ, Greenwood CE, Winocur G, Wolever TMS: Cognitive performance is associated with glucose regulation in healthy elderly persons and can be enhanced with glucose and dietary carbohydrates. Am J Clin Nutr 72:825–836, 2000[Abstract/Free Full Text]
   

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				C. E. Greenwood, R. J. Kaplan, S. Hebblethwaite, and D. J.A. Jenkins Memory Impairments Associated With Postprandial Hyperglycemia and Glycemic Control: Response to Kubiak et al. Diabetes Care, February 1, 2004; 27(2): 634 - 635. [Full Text] [PDF]

This Article Extract Full Text (PDF) Purchase Article View Shopping Cart Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Permissions Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Kubiak, T. Articles by Haak, T. Search for Related Content PubMed PubMed Citation Articles by Kubiak, T. Articles by Haak, T. Social Bookmarking                What's this?