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| News covering selected sessions related to migraine from 2008 medical conferences. |
| Annual Meeting of the American Academy of Neurology |
Chicago, IL April 15-18, 2008 |
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Excessively High, Low HbA1c Levels Carry
Elevated Dementia Risk |
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BY DENISE NAPOLI
Assistant Editor |
CHICAGO
— Excessively high and extremely low levels of
glycosylated hemoglobin were associated with an increased risk
for dementia in elderly patients with type 2 diabetes, according
to the findings of a cohort study involving more than 22,000
patients.
Dr. Rachel Whitmer surveyed a cohort of 22,852 patients older
than age 55 from the Kaiser Permanente Northern California
diabetes registry who had their HbA1c measured at least once
between 1994 and 1996, and checked these same patients’ records
again between Jan. 1, 1997, and May 30, 2006, for a diagnosis of
dementia, vascular dementia, or Alzheimer’s disease. People who
had a prior diagnosis of dementia at the initial survey were
excluded from the study.
In presenting the data at the annual meeting of the American
Academy of Neurology, Dr. Whitmer described the cohort, which
was 48% female and 35% nonwhite, as a “very diverse sample.” The
mean age at the time of the initial survey was 65 years.
A total of 2,488 participants (11%) were diagnosed with dementia
during the follow-up period. Patients with dementia were more
likely to be on insulin and have had a longer duration of
diabetes than were those without dementia, said Dr. Whitmer, an
investigator at the division of research, Kaiser Permanente
Northern California.
The researchers used a reference glycosylated hemoglobin level
of 7%, because this is the cutoff point that endocrinologists
aim for to lower the risks of complications.
Surprisingly, “we really did not see an elevated risk of
dementia until we got to values that were from 10% to 11.9% and
really 12% or greater,” she said.
Diabetic people with HbA1c values of 15% and above were 83% more
likely to receive a diagnosis of dementia during the follow-up
period than were their diabetic peers with glycosylated
hemoglobin levels under 7%.
Diabetics with values of 12% or more had a 22% elevated risk of
dementia.
However, the investigators also looked at people with extremely
low levels of HbA1c—less than 5%—and found that this group
actually had the greatest risk of dementia. People with levels
less than 5% were 2.2 times more likely to have dementia,
compared with patients with levels between 5% and 7%.
All risk assessments were made after adjusting for age,
education, race, sex, weight, treatment, diabetes duration,
hypertension, hyperlipidemia, heart disease, and stroke.
“Most endocrinologists like to aim for [HbA1c] levels less than
8% or less than 7%,” said Dr. Whitmer. “It’s been shown that
this lowers the risk of stroke and hypertension.” However,
physicians would do well to take into account these new cutoff
points for dementia risk in their assessment of patients. “When
we’re looking at elderly people with diabetes, overcontrol can
be just as much as a problem as not as much control,” Dr.
Whitmer said.
One of the study’s limitations is that HbA1c might have been
underestimated for those patients whose dementia went
undiagnosed. Furthermore, no brain imaging or cognitive tests
were available to confirm the dementia diagnoses. Future studies
are needed to confirm the findings.
It’s unknown what the mechanism would be that links HbA1c and
dementia, added Dr. Whitmer.
Dr. Whitmer reported no disclosures in relation to her
presentation. One of her fellow researchers on this study
disclosed relationships to Novartis Corp., Myriad Genetics Inc.,
and Posit Science. |
| Copyright 2008 Elsevier Custom Conference Coverage. All rights reserved. This material may not be published, broadcast, rewritten, or redistributed. All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior written permission of the copyright owner. No responsibility is assumed by the Publisher for any injury and/or damage to persons or property as a matter of products liability, through negligence or otherwise, or from any use or operation of any methods, products, instructions, or ideas contained in the material herein. Because of rapid advances in the medical sciences, the Publisher recommends that independent verification of diagnoses and drug dosages should be made. Opinions expressed in this publication are those of the original authors and do not necessarily reflect those of the Publisher, the sponsor, or the editors. Elsevier assumes no liability for any material published herein. |
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