Monday, July 15, 2013

Those with Type 2 Diabetes Have a 50% Greater Risk of Dementia


In diabetic patients those initiating metformin had a five year reduced risk of dementia in comparison to patients initiating other therapies. Is metformin the answer?

By +Bob DeMarco  
+Alzheimer's Reading Room 

Researchers studied a cohort of 14,891 patients aged 55+ in the Kaiser Permanente Diabetes Registry who initiated any diabetes pharmacotherapy between October 1999 and November 2001.

1487 (9.9 percent) patients were diagnosed with dementia in the 5 year follow-up period.




Anti-Hyperglycemic Therapy and Risk of Dementia: A New User Cohort Study

Presenting author: Rachel Whitmer, Rachel Whitmer*1, Charles Quesenberry Jr2, Jessica Allison2, Andy Karter1 1Kaiser Permanente Division of Research, Oakland, California, United States; 2Kaiser Permanente, Oakland, California, United State

The Gist
  • Even though those with type 2 diabetes (T2DM) have double the risk of dementia there’s a paucity of work examining the association between diabetes treatment and risk of dementia.
  • This is important in light of ongoing clinical trials evaluating insulin sensitizers as a potential treatment for mild cognitive impairment and Alzheimer’s disease.
  • The objective was to evaluate the impact of initiating new diabetes therapies on time-to-incident dementia in a new user cohort study of patients with T2DMs to adjust for confounding by indication.
The Highlight
  • Researchers studied a cohort of 14,891 T2DM patients aged 55+ in the Kaiser Permanente Diabetes Registry who initiated any diabetes pharmacotherapy between October 1999 and November 2001.
  • Only patients initiating single new therapies (“new users”) were included to reduce confounding and create mutually exclusive exposure groups.
  • Researchers constructed Cox proportional hazards models to evaluate the impact of initiating new diabetes therapies on time to dementia defined by medical record diagnoses made in visits to primary care, memory clinics and neurology from 1/1/2002-12/31/2007.
  • Models were adjusted for age, race, education and diabetes duration.
Results
  • 1487 (9.9 percent) patients were diagnosed with dementia in the 5 year follow-up period.
  • Of these 1487 patients 55 percent initiated Metformin, 25 percent Sulfonylurea, 14 percent Thiazolidinediones (TZDs), and 6 percent insulin.
  • With sulfonylureas as the reference group those initiating metformin had a 20 percent reduced risk of dementia (Hazards Ratio {HR},=0.79, 95 percent Confidence Interval {CI}, .65, .95), while those initiating TZD or insulin had no difference in risk.
  • In comparison to those initiating metformin, those initiating SU had a 24 percent increased risk (HR=1.24, 95 percent CI 1.1,1.4), TZDs an 18 percent increased risk (HR=1.18, 95 percent CI 1.1, 1.4) and insulin a 28 percent increased risk (HR=1.28, 1.1,1.6).
  • Findings were similar when models additionally adjusted for glycosylated hemoglobin.

Conclusion
  • In diabetic patients those initiating metformin had a five year reduced risk of dementia in comparison to patients initiating other therapies.
  • Animal models suggest metformin may contribute to neurogenesis and trials are evaluating metformin as a potential therapeutic for mild cognitive impairment. These results are preliminary evidence that benefits of insulin sensitizers may extend beyond glycemic control to neurocognitive health.
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