Retinal microcirculation changes in prediabetic patients with short-term increased blood glucose using optical coherence tomography angiography

Table 1 The average ages and male-to-female ratios of the control group, group 1, and group 2 were not significantly different (P > 0.05)

Group	Control (CN)	Group 1 (IFG or IGT)	Group 2 (IFG and IGT)	P value
Average age (years)	29.57 ± 3.92	30.79 ± 6.92	34.15 ± 8.53	0.248
Male to female ratio	2:21	1:13	2:11	0.707

CN: Control group; IFG: Impaired fasting glucose; IGT: Impaired glucose tolerance.

Table 2 Correlations between blood glucose levels and optical coherence tomography angiography indicators in the superficial retinal layer of the three groups

Index	Fasting		After OGTT
	Coefficient	P value	Coefficient	P value
Central VD	0.264	0.064	-0.145	0.314
Lateral VD	0.093	0.520	0.020	0.891
Full VD	0.148	0.306	-0.038	0.793
Central PD	0.286	0.044	-0.137	0.344
Lateral PD	0.127	0.379	0.038	0.792
Full PD	0.231	0.106	-0.016	0.915
FAZ area	-0.190	0.187	0.147	0.308
FAZ perimeter	-0.216	0.131	0.162	0.261
FAZ circularity	0.049	0.734	-0.079	0.5861

¹Correlations between blood glucose level and optical coherence tomography angiography metrics via Spearman’s correlation analysis; the others were evaluated via Pearson’s correlation analysis.

OGTT: Oral glucose tolerance test; VD: Vessel density; PD: Perfusion density; FAZ: Foveal avascular zone.

Table 3 Comparison of optical coherence tomography angiography indices in the superficial retina between fasting conditions and one hour after the oral glucose tolerance test

Index	CN (n = 23)		P value	Group 1 (n = 14)		P value	Group 2 (n = 13)		P value
	Fasting	Postprandial		Fasting	Postprandial		Fasting	Postprandial
Central VD	9.21 ± 2.35	9.74 ± 2.61	0.023	7.58 ± 2.82	7.81 ± 2.96	0.464	10.49 ± 2.50	10.37 ± 2.15	0.733
Lateral VD	21.44 ± 1.07	21.71 ± 1.29	0.268	21.35 ± 1.16	21.75 ± 1.03	0.321	21.44 ± 1.70	21.90 ± 1.21	0.7221
Full VD	20.06 ± 1.02	20.38 ± 1.28	0.186	19.79 ± 1.17	20.15 ± 1.12	0.347	20.21 ± 1.65	20.59 ± 1.14	0.8071
Central PD	0.15 ± 0.04	0.16 ± 0.04	0.026	0.13 ± 0.05	0.13 ± 0.05	0.662	0.18 ± 0.04	0.18 ± 0.04	0.616
Lateral PD	0.38 ± 0.02	0.38 ± 0.02	0.270	0.38 ± 0.02	0.39 ± 0.02	0.306	0.38 ± 0.03	0.39 ± 0.02	0.6491
Full PD	0.35 ± 0.02	0.36 ± 0.02	0.231	0.35 ± 0.02	0.36 ± 0.02	0.741	0.36 ± 0.03	0.36 ± 0.02	0.8341
FAZ area	0.31 ± 0.11	0.32 ± 0.11	0.207	0.41 ± 0.13	0.41 ± 0.13	0.716	0.28 ± 0.09	0.29 ± 0.09	0.357
FAZ perimeter	2.35 ± 0.38	2.34 ± 0.38	0.5811	2.73 ± 0.44	2.69 ± 0.45	0.232	2.26 ± 0.38	2.25 ± 0.36	0.509
FAZ circularity	0.70 ± 0.08	0.71 ± 0.07	0.602	0.69 ± 0.06	0.72 ± 0.05	0.023	0.69 ± 0.06	0.71 ± 0.08	0.162

¹Comparison between fasting conditions and one hour after the oral glucose tolerance test via the paired Wilcoxon signed-rank test; the other tests were paired t tests.

Group 1 comprised patients with either impaired fasting glucose (IFG) or impaired glucose tolerance (IGT); Group 2 comprised patients with both IFG and IGT. CN: Control group; VD: Vessel density; PD: Perfusion density; FAZ: Foveal avascular zone.

Table 4 Comparison of optical coherence tomography angiography indicators in the superficial retinal layer among the three groups during fasting

Index	CN (n = 23)	Group 1 (n = 14)	Group 2 (n = 13)	Statistics value	P value	P1	P2	P3
Central VD	9.21 ± 2.35	7.58 ± 2.82	10.49 ± 2.50	4.525	0.0161	0.188	0.455	0.013
Lateral VD	21.44 ± 1.07	21.35 ± 1.16	21.44 ± 1.70	0.026	0.9741
Full VD	20.06 ± 1.02	19.79 ± 1.17	20.21 ± 1.65	2.652	0.2662
Central PD	0.15 ± 0.04	0.13 ± 0.05	0.18 ± 0.04	4.999	0.0111	0.280	0.218	0.008
Lateral PD	0.38 ± 0.02	0.38 ± 0.02	0.38 ± 0.03	0.775	0.6792
Full PD	0.35 ± 0.02	0.35 ± 0.02	0.36 ± 0.03	2.078	0.3542
FAZ area	0.31 ± 0.11	0.41 ± 0.13	0.28 ± 0.09	5.312	0.0081	0.032	1.000	0.012
FAZ perimeter	2.35 ± 0.38	2.73 ± 0.44	2.26 ± 0.38	5.804	0.0061	0.018	1.000	0.010
FAZ circularity	0.70 ± 0.08	0.69 ± 0.06	0.69 ± 0.06	0.257	0.7751

¹Comparisons among groups were performed via one-way analysis of variance.

²Comparisons among groups were performed via the Kruskal-Wallis H test.

P1: Comparisons between the control group (CN) and group 1; P2: Comparisons between the CN and group 2; P3: Comparisons between group 1 and group 2. All P values were adjusted with the Bonferroni correction. Group 1 comprised patients with either impaired fasting glucose (IFG) or impaired glucose tolerance (IGT); Group 2 comprised patients with both IFG and IGT. CN: Control group; VD: Vessel density; PD: Perfusion density; FAZ: Foveal avascular zone.

Table 5 Comparison of oral glucose tolerance test indicators in the superficial retinal layer among the three groups after one hour of oral glucose tolerance test

Index	CN (n = 23)	Group 1 (n = 14)	Group 2 (n = 13)	Statistics value	P value	P1	P2	P3
Central VD	9.74 ± 2.61	7.81 ± 2.96	10.37 ± 2.15	3.706	0.032	0.101	1.000	0.042
Lateral VD	21.71 ± 1.29	21.75 ± 1.03	21.90 ± 1.21	0.106	0.899
Full VD	20.38 ± 1.28	20.15 ± 1.12	20.59 ± 1.14	0.449	0.641
Central PD	0.16 ± 0.04	0.13 ± 0.05	0.18 ± 0.04	4.271	0.020	0.092	1.000	0.022
Lateral PD	0.38 ± 0.02	0.39 ± 0.02	0.39 ± 0.02	0.093	0.911
Full PD	0.36 ± 0.02	0.36 ± 0.02	0.36 ± 0.02	0.241	0.787
FAZ area	0.32 ± 0.11	0.41 ± 0.13	0.29 ± 0.09	4.963	0.011	0.044	1.000	0.015
FAZ perimeter	2.34 ± 0.38	2.69 ± 0.45	2.25 ± 0.36	4.967	0.011	0.038	1.000	0.016
FAZ circularity	0.71 ± 0.07	0.72 ± 0.05	0.71 ± 0.08	0.115	0.891

P1: Comparisons between the control group (CN) and Group 1; P2: Comparisons between the CN and Group 2; P3: Comparison between Group 1 and Group 2. All P values were adjusted with the Bonferroni correction. Group 1 comprised patients with either impaired fasting glucose (IFG) or impaired glucose tolerance (IGT); Group 2 comprised patients with both IFG and IGT. P: Comparisons among groups were performed via one-way analysis of variance. CN: Control group; VD: Vessel density; PD: Perfusion density; FAZ: Foveal avascular zone.