title: Another look at the association between diabetes and keratoconus.
abstract: OBJECTIVE
  The aim of this study was to evaluate the association between diabetes mellitus (DM) and keratoconus.
  
  
  METHODS
  We conducted 2 substudies: (1) Retrospective comparison of the prevalence of DM in patients with keratoconus with that of control patients without keratoconus and (2) Cross-sectional study of the severity of keratoconus in diabetic keratoconus-affected patients and nondiabetic keratoconus-affected patients. Patients seen at the Wills Eye Hospital Cornea Service from January 2008 to August 2012 were included. Study 1 included 1377 patients with keratoconus and 4131 controls without keratoconus. Study 2 involved 75 type 2 diabetic keratoconus-affected patients and 225 nondiabetic keratoconus-affected patient, excluding patients with bilateral keratoplasty. In patients with a history of a corneal transplant in 1 eye, the other eye was included. Keratoconus severity was based on the topographic mean keratometry in the more severely affected eye.
  
  
  RESULTS
  Two of 1377 (0.15%) keratoconus-affected patients had type 1 DM, which was similar to that of 20 of the 4131 (0.49%) matched controls (P = 0.139). The prevalence of type 2 DM was higher in patients with keratoconus (93/1377, 6.75%) than in matched controls (200/4131, 4.84%) (P = 0.005). When categorized by age group, the prevalence of type 2 DM was higher in patients with keratoconus than in those without keratoconus in patients aged between 25 and 44 years (P = 0.036) and 45 and 64 years (P = 0.047). Using multinomial logistic regression analyses, the probability/risk of being in the severe keratoconus-affected group as opposed to the mild keratoconus-affected group was higher in patients with DM than in those without DM (P = 0.006; odds ratio = 2.691; 95% confidence interval, 1.330-5.445).
  
  
  CONCLUSIONS
  There may be a positive association between type 2 DM and the presence and severity of keratoconus.
authors.affiliation: Cornea Service, Wills Eye Hospital, Jefferson Medical College of Thomas Jefferson University, Philadelphia, PA.
authors.forename: Mustafa
authors.initials: M
authors.lastname: Kosker
authors.forename: Kunal
authors.initials: K
authors.lastname: Suri
authors.forename: Kristin M
authors.initials: KM
authors.lastname: Hammersmith
authors.forename: Ahmad H
authors.initials: AH
authors.lastname: Nassef
authors.forename: Parveen K
authors.initials: PK
authors.lastname: Nagra
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Rapuano
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016022:Case-Control Studies; D002648:Child; D019781:Corneal Topography; D003430:Cross-Sectional Studies; D003922:Diabetes Mellitus, Type 1 / Q000175:diagnosis / Q000453:epidemiology*; D003924:Diabetes Mellitus, Type 2 / Q000175:diagnosis / Q000453:epidemiology*; D005260:Female; D006801:Humans; D007640:Keratoconus / Q000175:diagnosis / Q000453:epidemiology*; D008297:Male; D008875:Middle Aged; D010414:Pennsylvania / Q000453:epidemiology; D015995:Prevalence; D012189:Retrospective Studies; D055815:Young Adult