title: Association of blood glucose control and pancreatic reserve with diabetic retinopathy in the Veterans Affairs Diabetes Trial (VADT).
abstract: OBJECTIVE
  The aim of this study was to test the hypothesis that intensive glycaemic control (INT) and higher plasma C-peptide levels in patients with poorly controlled diabetes would be associated with better eye outcomes.
  
  
  METHODS
  The incidence and progression of diabetic retinopathy (DR) was assessed by grading seven-field stereoscopic fundus photographs at baseline and 5 years later in 858 of 1,791 participants in the Veterans Affairs Diabetes Trial (VADT).
  
  
  RESULTS
  After adjustment for all covariates, risk of progression (but not incidence) of DR increased by 30% for each 1% increase in baseline HbA1c (OR 1.3; 95% CI 1.123, 1.503; p = 0.0004). Neither assignment to INT nor age was independently associated with DR in the entire cohort. However, INT showed a biphasic interaction with age. The incidence of DR was decreased in INT participants ≤55 years of age (OR 0.49; 95% CI 0.24, 1.0) but increased in those ≥70 years old (OR 2.88; 95% CI 1.0, 8.24) (p = 0.0043). The incidence of DR was reduced by 67.2% with each 1 pmol/ml increment in baseline C-peptide (OR 0.328; 95% CI 0.155, 0.7; p = 0.0037). Baseline C-peptide was also an independent inverse risk factor for the progression of DR, with a reduction of 47% with each 1 pmol/ml increase in C-peptide (OR 0.53; 95% CI 0.305, 0.921; p = 0.0244).
  
  
  CONCLUSIONS
  Poor glucose control at baseline was associated with an increased risk of progression of DR. INT was associated with a decreased incidence of DR in younger patients but with an increased risk of DR in older patients. Higher C-peptide at baseline was associated with reduced incidence and progression of DR.
authors.affiliation: Endocrinology Section, Edward Hines, Jr VA Hospital, Building 1, Room D139, Hines, IL, 60141, USA, Nasrin.azad@va.gov.
authors.forename: Nasrin
authors.initials: N
authors.lastname: Azad
authors.forename: Lily
authors.initials: L
authors.lastname: Agrawal
authors.forename: Nicholas V
authors.initials: NV
authors.lastname: Emanuele
authors.forename: Ronald
authors.initials: R
authors.lastname: Klein
authors.forename: Gideon D
authors.initials: GD
authors.lastname: Bahn
authors.forename: Peter
authors.initials: P
authors.lastname: Reaven
mesh_terms: D000368:Aged; D001786:Blood Glucose / Q000378:metabolism*; D002096:C-Peptide / Q000378:metabolism; D003924:Diabetes Mellitus, Type 2 / Q000097:blood* / Q000378:metabolism*; D003930:Diabetic Retinopathy; D005260:Female; D006442:Glycated Hemoglobin / Q000378:metabolism; D006801:Humans; D008297:Male; D008875:Middle Aged; D010179:Pancreas / Q000378:metabolism*; D014728:Veterans
chemical_list: D001786:Blood Glucose; D002096:C-Peptide; D006442:Glycated Hemoglobin