Table 2.

Mean differences in flicker light–induced vasodilation between participants with diabetes and normal control subjects and by grades of diabetic retinopathy severity in participants with diabetes

Groups	n	Mean dilation	Age- and sex-adjusted		Multivariable adjusted*
			Mean difference (95% CI)	P	Mean difference (95% CI)	P
Arteriolar
Control subjects	103	3.46	(Reference)		(Reference)
Diabetic patients	224	1.43	−1.87 (−1.43 to −2.31)	<0.001	−1.58 (−1.05 to −2.11)	<0.001
Type 1 diabetes		1.57	−1.99 (−1.46 to −2.52)	<0.001	−1.71 (−1.10 to −2.32)	<0.001
Type 2 diabetes		1.24	−1.78 (−1.29 to −2.27)	<0.001	−1.48 (−0.90 to −2.07)	<0.001
Diabetic retinopathy severity
None		1.76	(Reference)		(Reference)
Minimal NPDR		1.39	−0.37 (0.29 to −1.03)	0.28	−0.53 (0.16 to −1.22)	0.13
Early-moderate NPDR		1.01	−0.75 (−0.23 to −1.28)	0.005	−0.85 (−0.29 to −1.40)	0.003
Severe NPDR		1.24	−0.51 (0.15 to −1.16)	0.13	−0.58 (0.12 to −1.28)	0.10
Venular
Control subjects		3.98	(Reference)		(Reference)
Diabetic patients		2.83	−0.98 (−0.57 to −1.39)	<0.001	−1.07 (−0.56 to −1.57)	<0.001
Type 1 diabetes		2.84	−1.11 (−0.62 to −1.61)	<0.001	−1.36 (−0.78 to −1.94)	<0.001
Type 2 diabetes		2.83	−0.88 (−0.42 to −1.34)	<0.001	−0.83 (−0.27 to −1.38)	0.004
Diabetic retinopathy severity
None		3.19	(Reference)		(Reference)
Minimal NPDR		2.94	−0.49 (0.10 to −1.09)	0.10	−0.10 (0.60 to −0.79)	0.78
Early-moderate NPDR		2.40	−1.11 (−0.63 to −1.58)	<0.001	−0.67 (−0.11 to −1.23)	0.02
Severe NPDR		2.32	−1.16 (−0.55 to −1.77)	<0.001	−0.65 (0.06 to −1.35)	0.07

Data are %.

*Adjustment for age, sex, fasting cholesterol and triglyceride levels, use of antihypertensive and lipid-lowering medications, current smoking status, and fasting glucose (for analysis of diabetic retinopathy severity).