title: Short-term stability in refractive status despite large fluctuations in glucose levels in diabetes mellitus type 1 and 2.
abstract: OBJECTIVE
  This work investigates how short-term changes in blood glucose concentration affect the refractive components of the diabetic eye in patients with long-term Type 1 and Type 2 diabetes.
  
  
  METHODS
  Blood glucose concentration, refractive error components (mean spherical equivalent MSE, J0, J45), central corneal thickness (CCT), anterior chamber depth (ACD), crystalline lens thickness (LT), axial length (AL) and ocular aberrations were monitored at two-hourly intervals over a 12-hour period in: 20 T1DM patients (mean age ± SD) 38±14 years, baseline HbA1c 8.6±1.9%; 21 T2DM patients (mean age ± SD) 56±11 years, HbA1c 7.5±1.8%; and in 20 control subjects (mean age ± SD) 49±23 years, HbA1c 5.5±0.5%. The refractive and biometric results were compared with the corresponding changes in blood glucose concentration.
  
  
  RESULTS
  Blood glucose concentration at different times was found to vary significantly within (p<0.0005) and between groups (p<0.0005). However, the refractive error components and ocular aberrations were not found to alter significantly over the day in either the diabetic patients or the control subjects (p>0.05). Minor changes of marginal statistical or optical significance were observed in some biometric parameters. Similarly there were some marginally significant differences between the baseline biometric parameters of well-controlled and poorly-controlled diabetic subjects.
  
  
  CONCLUSIONS
  This work suggests that normal, short-term fluctuations (of up to about 6 mM/l on a timescale of a few hours) in the blood glucose levels of diabetics are not usually associated with acute changes in refractive error or ocular wavefront aberrations. It is therefore possible that factors other than refractive error fluctuations are sometimes responsible for the transient visual problems often reported by diabetic patients.
authors.affiliation: Division of Optometry and Visual Science, City University London, London, United Kingdom.
authors.forename: Byki
authors.initials: B
authors.lastname: Huntjens
authors.forename: W Neil
authors.initials: WN
authors.lastname: Charman
authors.forename: Helena
authors.initials: H
authors.lastname: Workman
authors.forename: Sarah L
authors.initials: SL
authors.lastname: Hosking
authors.forename: Clare
authors.initials: C
authors.lastname: O'Donnell
mesh_terms: D000328:Adult; D000368:Aged; D001786:Blood Glucose / Q000502:physiology*; D016022:Case-Control Studies; D003315:Cornea / Q000503:physiopathology; D003922:Diabetes Mellitus, Type 1 / Q000097:blood / Q000150:complications / Q000503:physiopathology*; D003924:Diabetes Mellitus, Type 2 / Q000097:blood / Q000150:complications / Q000503:physiopathology*; D003930:Diabetic Retinopathy / Q000503:physiopathology; D018450:Disease Progression; D005123:Eye / Q000503:physiopathology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012029:Refraction, Ocular / Q000502:physiology*; D012030:Refractive Errors / Q000209:etiology / Q000503:physiopathology; D013997:Time Factors; D055815:Young Adult
chemical_list: D001786:Blood Glucose