Metformin Treatment Is Associated with a Decreased Risk of Nonproliferative Diabetic Retinopathy in Patients with Type 2 Diabetes Mellitus: A Population-Based Cohort Study

Table 3

Dose–response relation for risk of NPDR among DM patients after propensity score matching.

	DM patients without taking metformin	≤360 DDDs	361–720 DDDs	721–1080 DDDs	1081–1440 DDDs	>1440 DDDs
	5022	2295	1312	637	357	421
NPDR (, %)	578 (11.51)	262 (11.42)	162 (12.35)	70 (10.99)	29 (8.12)	32 (7.60)
NPDR onset time (years, )
Crude HR (95% CI)	Reference	0.95 (0.82–1.09)	0.73 (0.61–0.87)	0.53 (0.42–0.68)	0.33 (0.23–0.48)	0.27 (0.19–0.39)
Adjusted HR (95% CI)	Reference	0.99 (0.84–1.17)	0.77 (0.63–0.93)	0.53 (0.40–0.69)	0.33 (0.22–0.49)	0.29 (0.19–0.43)
value		0.9115	0.0074	<0.0001	<0.0001	<0.0001
for trend				0.0254^§
				0.0096^¶

Adjusted for gender, age, comorbidities, medications, aDCSI scores, DM duration, and other antidiabetic drugs use. ^§Dose–response relation among DM patients. ^¶Dose–response relation among DM patients with taking metformin. NPDR: nonproliferative diabetic retinopathy; DDD: defined daily dose; aDCSI scores: adapted Diabetes Complications Severity Index scores; DM: diabetes mellitus; HR: hazard ratio.