Table 1 Basic characteristics among the study and control groups

Age

1.0000

1.0000

 < 40

672 (5.1%)

672 (5.1%)

168 (5.1%)

 40–59

7168 (54.35%)

7168 (54.35%)

1792 (54.35%)

 60–79

5048 (38.28%)

5048 (38.28%)

1262 (38.28%)

 > =80

300 (2.27%)

300 (2.27%)

75 (2.27%)

Gender

1.0000

1.0000

 Male

6872 (52.11%)

6872 (52.11%)

1718 (52.11%)

 Female

6316 (47.89%)

6316 (47.89%)

1579 (47.89%)

 Hypertension

4441 (33.67%)

8696 (65.94%)

2321 (70.4%)

< 0.0001*

< 0.0001*

 Ischemic heart diseases

1573 (11.93%)

2977 (22.57%)

653 (19.81%)

< 0.0001*

0.0006*

 Hyperlipidemia

3425 (25.97%)

8751 (66.36%)

2134 (64.73%)

< 0.0001*

0.0771

 Congestive heart failure

567 (4.3%)

1260 (9.55%)

324 (9.83%)

< 0.0001*

0.6343

 Cerebrovascular disease

1255 (9.52%)

2135 (16.19%)

530 (16.08%)

< 0.0001*

0.8739

 Dementia

193 (1.46%)

262 (1.99%)

35 (1.06%)

0.0772

0.0004*

 Chronic pulmonary diseases

2736 (20.75%)

3763 (28.53%)

715 (21.69%)

0.2353

< 0.0001*

 Rheumatoid arthritis as well as osteoarthritis

367 (2.78%)

442 (3.35%)

102 (3.09%)

0.3369

0.4586

 Kidney disease

695 (5.27%)

1507 (11.43%)

493 (14.95%)

< 0.0001*

< 0.0001*

 Hepatitis and liver cirrhosis

3080 (23.35%)

5511 (41.79%)

1032 (31.3%)

< 0.0001*

< 0.0001*

 Alcoholic liver disease

125 (0.95%)

401 (3.04%)

82 (2.49%)

< 0.0001*

0.0919

 Gout

1642 (12.45%)

3079 (23.35%)

547 (16.59%)

< 0.0001*

< 0.0001*

 Atopic dermatitis

475 (3.6%)

667 (5.06%)

133 (4.03%)

0.2389

0.0144*

 Allergic otolaryngologic diseases

2705 (20.51%)

3067 (23.26%)

563 (17.08%)

< 0.0001*

< 0.0001*

 DED

1093 (8.29%)

1241 (9.41%)

466 (14.13%)

< 0.0001*

< 0.0001*

 Uveitis

111 (0.84%)

122 (0.93%)

139 (4.22%)

< 0.0001*

< 0.0001*

 Glaucoma

297 (2.25%)

376 (2.85%)

270 (8.19%)

< 0.0001*

< 0.0001*

 AMD

130 (0.99%)

157 (1.19%)

172 (5.22%)

< 0.0001*

< 0.0001*

 Retinal diseases warrant trans pars plana vitrectomy

19 (0.14%)

11 (0.08%)

181 (5.49%)

< 0.0001*

< 0.0001*

 Systemic steroid

1974 (14.97%)

2676 (20.29%)

752 (22.81%)

< 0.0001*

0.0014*

 Topical steroid

1737 (13.17%)

2048 (15.53%)

1810 (54.9%)

< 0.0001*

< 0.0001*

 Phenothiazines

385 (2.92%)

671 (5.09%)

236 (7.16%)

< 0.0001*

< 0.0001*

 Amiodarone

54 (0.41%)

136 (1.03%)

26 (0.79%)

0.0051*

0.2065

 Statin

993 (7.53%)

4069 (30.85%)

1348 (40.89%)

< 0.0001*

< 0.0001*

 Metformin

397 (3.01%)

6558 (49.73%)

2510 (76.13%)

< 0.0001*

< 0.0001*

 Other oral hypoglycemic agents

160 (1.21%)

7489 (56.79%)

2787 (84.52)

< 0.0001*

< 0.0001*

 Insulin

3 (0.02%)

1536 (11.67%)

1736 (52.64%)

< 0.0001*

< 0.0001*

Duration of DM (years)

1.0000

1.0000

 0

13,188 (100%)

0 (0%)

0 (0%)

 < 2

0 (0%)

6456 (48.95%)

1614 (48.95%)

 2–5

0 (0%)

3828 (29.03%)

957 (29.03%)

 ≥ 5

0 (0%)

2904 (22.02%)

726 (22.02%)

Type of DR

–

–

 Without DR

13,188 (100%)

13,188 (100%)

0 (0%)

 NPDR

0 (0%)

0 (0%)

1788 (54.23%)

 PDR

0 (0%)

0 (0%)

1509 (45.77%)