Hide Sidebar

Hypoglycemic Events in Older Patients with Type 2 DM increases risk of dementia

Hypoglycemic Events in Older Patients with Type 2 DM increases risk of dementia

Critique date: Thu, 05/07/2009 - 3:28pm
Institution: 
Mount Sinai School of Medicine
   
Article Citation
Citation: 
JV Whitmer, RA Karter, AJ Yaffe, K Quesenberry, CP Selby, JV Hypoglycemic Episodes and Risk of Dementia in Older Patients with Type 2 Diabetes Mellitus. JAMA 2009 301(15) 1565-1572.
   
Clinical Bottom Lines
  1. Older type 2 diabetics with any incidence of hypoglycemia warranting an ED visit or hospitalization have a 2.39 increased risk of dementia per year than diabetics without hypoglycemic events
  2. Diabetic patients that are African American, have ESRD, h/o CVA, HTN or are on insulin are more likely to have hypoglycemic episodes.
   
Methods
Study Design: 
Cohort study
Follow-up Period: 
The incidences of hypoglycemia were followed for 22 years and then the incidence of dementia was evaluated for four years.
Patient Population: 

16,667 patients drawn from the Kasier Permamente Diabetes registry

Mean age between 64-66, approximately 60% white

 

Inclusion Criteria: All patients were surveyed via mail-those included in the study

  1. returned the survey
  2. were aged 55+ at the time of survey
  3. alive
  4. no previous diagnosis of dementia, mild cognitive impairment or memory loss
Significant Exclusions: 

Those with an established diagnosis of dementia, MCI or memory problems

Intervention/Exposure: 

As this was a harm study and was a retrospective cohort, there was no intervention per se-instead the incidence of ED visits or hospitalizations due to hypoglycemia were counted. The ICD-9 codes for hypoglycemia was used as a marker and episodes from 1/1/80 through 12/31/02 were included

To evaluate for incident cases of dementia ICD-9 codes were also utilized starting in 2003

Outcome Measures: 

Primary Outcome: “To determine whether prior episodes of hypoglycemia that required hospitalization or emergency department visits are associated with an increased risk of dementia during 22 years of follow-up for hypoglycemia episodes and more than 4 years of follow-up for incident dementia in a large well-characterized cohort of older patients with type 2 diabetes.”

Secondary Outcomes: no defined secondary outcomes however patients with CVA, ESRD, African American and those with ED visits only were looked at.

The study did have two subgroups to eliminate or reduce the risk of reverse causality (i.e. that patients with dementia may have more hypoglycemic episodes)

  1. Two year Lag: started evaluating for incident cases of dementia in 2005 rather than 2003
  2. Backward lag of 18 years: only looked at hypoglycemic events in the first five years (1980-1985)
Participant Follow-up: 
There was no patient drop out as this was a retrospective cohort study.
   
Conclusion
Results: 

Analysis: ITT not applicable in the retrospective cohort model

Results:

 

Dementia

(n=1822)

Nondementia

(n=14,845)

Age adjusted Incidence per 10,000 person years

Excess Attributable Risk per year, %

Any hypoglycemia

 

 

 

 

 

           NO

1572

13, 630

327.6 (311.02-343.18)

 

           YES

250

1215

566.82(496.52-637.48)

2.39 (1.72-3.01)

# of hypoglycemic episodes

 

 

 

 

           0

1572

13,630

327.6 (311.02-343.18)

 

           1

150

852

491.73 (412.6-570.8)

1.64 (0.91-2.36)

           2

57

201

761.75 (561.24-962.27)

4.34 (2.36-6.32)

           3

43

162

755.46 (526.46-984.46)

4.28 (2.1-6.44)

 

Patients with one or more hypoglycemic episodes when adjusted for age, BMI, Race, Education, Sex, Duration of DM: HR 1.68 (1.47-1.93) for yearly risk of incident dementia

Concerns Regarding Methodology, Applicability to Older Adults, etc.: 
  1. ICD-9 codes were selected for senile dementia, vascular dementia etc however MCI was not evaluated.  It would be helpful to include a subset of patients with milder memory loss and see if it is correlated to development of diabetes.
  2. Duration of Diabetes was obtained via patients self-report on the survey-this may not be accurate.
  3. Were not able to do baseline cognitive testing on all participants because of the scale of the study-but taking a smaller cohort and doing mini-cog before and after would be a beneficial exercise.
  4. They never tell us in the study how the cases of dementia are diagnosed, simply that the ICD-9 codes are appearing-is this a standardized diagnosis-who is making the diagnosis? Neurologists? Geriatricians? Psychiatrists?
  5. The hypoglycemic episodes could be-this would be a reason to do a mini-cog on everyone to start
  6. What about less severe but more frequent episodes of hypoglycemia-ones that can be managed at home with some juice…these may be more common and could have an impact.
Funding Source and Role: 
National Institutes of Health grants DK066308 and DK 081786
Created By: 
Allison B. Margold, MD. First Year Fellow, Geriatrics, Mt. Sinai
This is a review of the validity of a single study; the ‘bottom lines’ do not reflect comparison with the rest of the literature on this subject.