Correlation Between Thyroid-Related Hormones and Diabetic Retinopathy in Type 2 Diabetes Mellitus Patients with Normal Thyroid Function: A Retrospective Study

Figures & data

Table 1 Clinical Characteristics of Included Patients

Variables		DR Group (n=101)	NDR Group (n=185)	χ^2/t/Z	P-value
Sex	Male	68(23.78%)	110(38.46%)	1.721	0.19
	Female	33(11.54%)	75(26.22%)
Age (years)		62.52±11.89	58.98±12.05	2.386	0.018
BMI (kg/m^2)		21.51±3.73	21.22±3.98	0.593	0.554
Duration of diabetes (years)		8.30(4.00–12.00)	5.43(3.00–8.00)	−5.256	<0.001
Hypertension (case, %)	Yes	64(22.38%)	72(24.67%)	15.657	<0.001
	No	37(25.17%)	113(39.51%)
Coronary heart disease (case, %)	Yes	31(10.84%)	69(24.48%)	1.253	0.263
	No	70(24.13%)	116(40.56%)
Drinking (case, %)	Yes	41(14.34%)	70(24.48%)	0.209	0.648
	No	60(20.98%)	115(40.21%)
Smoking (case, %)	Yes	45(15.73%)	77(26.92%)	0.23	0.632
	No	56(34.15%)	108(37.76%)

Note: Data are expressed as mean ± standard deviation, median (quartile 25, quartile 75) or numbers (%).

Abbreviations: BMI, body mass index; DR, diabetic retinopathy; NDR, non-diabetic retinopathy.

Figure 1 Flow chart of case screening.

Abbreviations: T2DM, type 2 diabetes mellitus; DR, diabetic retinopathy; NDR, non-diabetic retinopathy.

Table 2 Comparison of Thyroid-Related Hormones, Blood Sugar and Blood Lipid Levels

Variables	DR Group (n=101)	NDR Group (n=185)	χ^2/t	P-value
HDL-C (mmol/L)	1.11±0.32	1.04±0.33	1.857	0.064
LDL-C (mmol/L)	3.33(1.69–4.51)	2.84(1.71–4.02)	−2.082	0.037
TC (mmol/L)	5.51±1.52	5.73±1.62	−1.139	0.256
TG(mmol/L)	3.03(2.15–3.94)	1.96(0.98–2.74)	−6.384	<0.001
FBG (mmol/L)	9.91±2.26	8.92±2.28	3.502	0.001
HbA1c (%)	12.72(9.26–16.06)	10.08(7.77–12.54)	−5.883	<0.001
TSH (mIU/L)	2.90±1.41	1.96±0.97	6.625	<0.001
FT3 (pmol/L)	4.60(3.74–5.30)	5.29(4.15–6.39)	−4.681	<0.001
FT4 (pmol/L)	11.76±2.30	12.02±2.42	−0.878	0.38

Note: Data are expressed as mean ± standard deviation, median (quartile 25, quartile 75) or numbers (%).

Abbreviations: HDL-C, high-density lipoprotein cholesterol; LDL-C, low-density lipoprotein cholesterol; TC, total cholesterol; TG, triglycerides; FBG, fasting blood glucose; HbA1c, glycated hemoglobin; TSH, thyroid stimulating hormone; FT3, free triiodothyronine; FT4, free thyroxine; DR, diabetic retinopathy; NDR, non-diabetic retinopathy.

Table 3 Logistics Regression Analysis for the Risk Factors of Diabetic Retinopathy

Variables	Univariate			Multivariate
	OR	95% CI	P-value	OR	95% CI	P-value
HDL-C	2.026	0.957–4.289	0.065	—	—	—
LDL-C	1.222	1.043–1.431	0.013	1.099	0.916–1.319	0.309
TC	0.914	0.784–1.067	0.255	—	—	—
TG	1.979	1.592–2.461	<0.001	1.435	1.119–1.840	0.004
FBG	1.202	1.077–1.342	0.001	1.14	1.005–1.293	0.042
HbA1c	1.289	1.187–1.400	<0.001	1.187	1.084–1.301	<0.001
TSH	1.948	1.557–2.436	<0.001	1.493	1.142–1.951	0.003
FT3	0.582	0.465–0.729	<0.001	0.752	0.582–0.972	0.03
FT4	0.955	0.863–1.058	0.955	—	—	—

Abbreviations: OR, Odds ratio; CI, confidence interval; HDL-C, high-density lipoprotein cholesterol; LDL-C, low-density lipoprotein cholesterol; TC, total cholesterol; TG, triglycerides; FBG, fasting blood glucose; HbA1c, glycated hemoglobin; TSH, thyroid stimulating hormone; FT3, free triiodothyronine; FT4, free thyroxine.

Figure 2 Comparison of FBG, HbA1c or TG at different TSH levels in diabetic retinopathy patients. *P < 0.05, **P < 0.01.

Abbreviations: TG, triglycerides; FBG, fasting blood glucose; HbA1c, glycated hemoglobin; TSH, thyroid stimulating hormone.

Figure 3 Comparison of FBG, HbA1c or TG at different FT3 levels in diabetic retinopathy patients. *P < 0.05, **P < 0.01.

Abbreviations: TG, triglycerides; FBG, fasting blood glucose; HbA1c, glycated hemoglobin; FT3, free triiodothyronine.

Table 4 Multivariate Linear Regression Analysis of TSH and FT3 Levels

Items	TSH			FT3
	β	t	P-value	β	t	P-value
TG	0.711	10.051	<0.001	−0.468	−5.354	<0.001
FBG	0.019	0.258	0.797	−0.212	−1.399	0.017
HbA1c	0.102	1.369	0.174	−0.118	−2.419	0.165

Abbreviations: TG, triglycerides; FBG, fasting blood glucose; HbA1c, glycated hemoglobin; TSH, thyroid stimulating hormone; FT3, free triiodothyronine.

Figure 4 Correlation of TSH or FT3 with FBG, HbA1c or TG in diabetic retinopathy patients.

Abbreviations: TG, triglycerides; FBG, fasting blood glucose; HbA1c, glycated hemoglobin; TSH, thyroid stimulating hormone; FT3, free triiodothyronine.