Table 4. Unadjusted and adjusted odds ratios and 95% confidence intervals for diabetic retinopathy and non-proliferative diabetic retinopathy according to the daily sunlight exposure duration divided by the duration of diabetes in Korean adults.

Multivariate Model	Model 1 OR (95% CI)	Model 2 OR (95% CI)	Model 3 OR (95% CI)
Diabetic duration <10 years
DR
Sunlight exposure <5 h	Reference	Reference	Reference
Sunlight exposure ≥5 h	2.18 (0.75–6.33) P = 0.150	3.58 (1.08–11.88) P = 0.037	4.26 (1.20–15.16) P = 0.025
NPDR
Sunlight exposure <5 h	Reference	Reference	Reference
Sunlight exposure ≥5 h	2.37 (0.81–6.95) P = 0.115	3.86 (1.14–13.02) P = 0.030	4.82 (1.32–17.59) P = 0.017
Diabetic duration ≥10 years
DR
Sunlight exposure <5 h	Reference	Reference	Reference
Sunlight exposure ≥5 h	1.26 (0.64–2.50) P = 0.507	1.09 (0.53–2.25) P = 0.825	1.20 (0.56–2.60) P = 0.636
NPDR
Sunlight exposure <5 h	Reference	Reference	Reference
Sunlight exposure ≥5 h	1.32 (0.66–2.65) P = 0.440	1.16 (0.56–2.40) P = 0.691	1.21 (0.55–2.62) P = 0.638

OR, odds ratio; CI, confidence interval; DR, diabetic retinopathy; NPDR, non-proliferative diabetic retinopathy.

Data from the 2008–2011 Korean National Health and Nutrition Examination Survey.

Model 1 was crude.

Model 2 was adjusted for age, sex, duration of diabetes, hemoglobin A1c level, and body mass index.

Model 3 was adjusted for serum 25-hydroxyvitamin D level, hypertension, dyslipidemia, smoking, and alcohol intake in addition to the variables adjusted in Model 2.