Table 2.

Risk of NPDR and STDR in patients with type 2 diabetes after propensity score matching.

	Metformin user events (total)	Metformin nonuser events (total)	Crude HR (95% CI)	Adjusted HR (95% CI)
NPDR	555/5022	578/5022	0.65 (0.58–0.73)	0.76 (0.68–0.87)
STDR	43/5022	68/5022	0.39 (0.27–0.58)	0.29 (0.19–0.45)
STDR among NPDR patients∗	43/860	14/182	0.50 (0.27–0.92)	0.54 (0.28–1.01)

^∗NPDR patients were those who received any oral antidiabetic drugs after the diagnosis of NPDR among the study population. NPDR: nonproliferative diabetic retinopathy; STDR: sight-threatening diabetic retinopathy; HR: hazard ratio.