title: Long-term effect of diabetes and its treatment on cognitive function.
abstract: BACKGROUND
  Long-standing concern about the effects of type 1 diabetes on cognitive ability has increased with the use of therapies designed to bring glucose levels close to the nondiabetic range and the attendant increased risk of severe hypoglycemia.
  
  
  METHODS
  A total of 1144 patients with type 1 diabetes enrolled in the Diabetes Control and Complications Trial (DCCT) and its follow-up Epidemiology of Diabetes Interventions and Complications (EDIC) study were examined on entry to the DCCT (at mean age 27 years) and a mean of 18 years later with the same comprehensive battery of cognitive tests. Glycated hemoglobin levels were measured and the frequency of severe hypoglycemic events leading to coma or seizures was recorded during the follow-up period. We assessed the effects of original DCCT treatment-group assignment, mean glycated hemoglobin values, and frequency of hypoglycemic events on measures of cognitive ability, with adjustment for age at baseline, sex, years of education, length of follow-up, visual acuity, self-reported sensory loss due to peripheral neuropathy, and (to control for the effects of practice) the number of cognitive tests taken in the interval since the start of the DCCT.
  
  
  RESULTS
  Forty percent of the cohort reported having had at least one hypoglycemic coma or seizure. Neither frequency of severe hypoglycemia nor previous treatment-group assignment was associated with decline in any cognitive domain. Higher glycated hemoglobin values were associated with moderate declines in motor speed (P=0.001) and psychomotor efficiency (P<0.001), but no other cognitive domain was affected.
  
  
  CONCLUSIONS
  No evidence of substantial long-term declines in cognitive function was found in a large group of patients with type 1 diabetes who were carefully followed for an average of 18 years, despite relatively high rates of recurrent severe hypoglycemia. (ClinicalTrials.gov number, NCT00360893.)
authors.forename: Alan M
authors.initials: AM
authors.lastname: Jacobson
authors.forename: Gail
authors.initials: G
authors.lastname: Musen
authors.forename: Christopher M
authors.initials: CM
authors.lastname: Ryan
authors.forename: Nancy
authors.initials: N
authors.lastname: Silvers
authors.forename: Patricia
authors.initials: P
authors.lastname: Cleary
authors.forename: Barbara
authors.initials: B
authors.lastname: Waberski
authors.forename: Amanda
authors.initials: A
authors.lastname: Burwood
authors.forename: Katie
authors.initials: K
authors.lastname: Weinger
authors.forename: Meg
authors.initials: M
authors.lastname: Bayless
authors.forename: William
authors.initials: W
authors.lastname: Dahms
authors.forename: Judith
authors.initials: J
authors.lastname: Harth
mesh_terms: D000328:Adult; D003071:Cognition; D003072:Cognition Disorders / Q000209:etiology; D003922:Diabetes Mellitus, Type 1 / Q000097:blood / Q000188:drug therapy / Q000523:psychology*; D003926:Diabetic Coma / Q000209:etiology / Q000523:psychology; D005260:Female; D005500:Follow-Up Studies; D006442:Glycated Hemoglobin / Q000032:analysis*; D006801:Humans; D007003:Hypoglycemia / Q000150:complications / Q000523:psychology*; D007004:Hypoglycemic Agents / Q000008:administration & dosage; D007328:Insulin / Q000008:administration & dosage; D008297:Male; D008875:Middle Aged; D011581:Psychological Tests; D012640:Seizures / Q000209:etiology
chemical_list: D006442:Glycated Hemoglobin; D007004:Hypoglycemic Agents; D007328:Insulin