Association Between Dietary Salt and Plasma Glucose, Insulin and Hemoglobin A_1c Levels Among Type 2 Diabetes Patients in Eastern China

Figures & data

Table 1 Patient Characteristics According to Levels of Salt Intake

	Total (n=1145)	≤6 g/day (n=286)	6–8 g/day (n=443)	>8 g/day (n=416)	P*
	Mean (SD)
Age (years)	51.4 (11.7)	50.9 (12.3)	51.8 (11.4)	51.3 (11.6)	0.596
Duration of type 2 diabetes (years)	7.5 (6.4)	7.4 (6.7)	7.8 (6.3)	7.2 (6.4)	0.409
Physical activity (minutes/week)	464.2 (1217.6)	481.3 (928.3)	481.7 (1542.3)	433.5 (979.6)	0.814
	No. (%)
Sex					0.216
Male	746 (65.2)	178 (62.2)	284 (64.1)	284 (68.3)
Female	399 (34.8)	108 (37.8)	159 (35.9)	132 (31.7)
Education					0.563
Low education	537 (46.9)	134 (46.9)	200 (45.1)	203 (48.8)
High education	608 (53.1)	152 (53.1)	243 (54.9)	213 (51.2)
Current smoking status					0.012
No	782 (68.3)	214 (74.8)	301 (67.9)	267 (64.2)
Yes	363 (31.7)	72 (25.2)	142 (32.1)	149 (35.8)
Current drinking status					0.001
No	654 (57.1)	189 (66.1)	247 (55.8)	218 (52.4)
Yes	491 (42.9)	97 (33.9)	196 (44.2)	198 (47.6)
Weight status					0.025
Underweight	243 (21.2)	63 (22.0)	76 (17.2)	104 (25.0)
Normal weight	414 (36.2)	109 (38.1)	177 (40.0)	128 (30.8)
Overweight	480 (41.9)	113 (39.5)	185 (41.8)	182 (43.8)
Obesity	8 (0.7)	1 (0.3)	5 (1.1)	2 (0.5)
Waist circumference status					<0.001
Normal	533 (46.6)	148 (51.7)	229 (51.7)	156 (37.5)
Central obesity	612 (53.4)	138 (48.3)	214 (48.3)	260 (62.5)
Hypertension					0.218
Yes	453 (39.6)	105 (36.7)	170 (38.4)	178 (42.8)
Hyperlipidemia					0.933
Yes	600 (52.4)	148 (517)	231 (52.1)	221 (53.1)
Hyperuricemia					0.354
Yes	202 (17.6)	45 (15.7)	75 (16.9)	82 (19.7)
Coronary disease					0.509
Yes	48 (4.2)	12 (4.2)	22 (5.0)	14 (3.4)
Stroke					0.339
Yes	37 (3.2)	13 (4.5)	13 (2.9)	11 (2.6)
Medication for hypertension†					0.287
Yes	417 (36.7)	97 (33.9)	157 (35.4)	163 (39.2)
Medication for hyperlipidemia†					0.320
Yes	316 (27.6)	89 (31.1)	118 (26.6)	109 (26.2)
Medication for hyperuricemia†					0.938
Yes	30 (2.6)	8 (2.8)	12 (2.7)	10 (2.4)

Notes: *Statistical values for continuous variables and categorical variables were obtained from analysis of variance and chi-square test, respectively. †The total sample of medication for hypertension was 1140; the total sample of medication for hyperlipidemia and medication for hyperuricemia was 1142.

Abbreviation: SD, standard deviation.

Table 2 Mean and Median Values of Risk Factors for Type 2 Diabetes According to Salt Intake Levels

Factors*	≤6 g/day (n=286)	6–8 g/day (n=443)	>8 g/day (n=416)	P
BMI (kg/m^2)	25.2 (3.8)	24.9 (3.6)	25.9 (3.8)^a,d	<0.001
WC (cm)	87.6 (10.6)	87.9 (9.7)	90.4 (9.5)^b,d	<0.001
VFA (cm^2)	87.7 (40.1)	89.9 (40.3)	99.8 (38.7)^b,d	<0.001
SFA (cm^2)	175.9 (3.9)	174.0 (60.6)	189.0 (64.6)^a,c	0.001
SBP (mmHg)	133.1 (17.7)	131.2 (17.7)	133.8 (18.3)	0.088
DBP (mmHg)	79.3 (11.5)	78.8 (11.0)	79.8 (10.6)	0.405
FPG (mmol/L)	8.1 (3.0)	8.7 (2.9)	8.9 (3.0)^a,c	0.005
2hPG (mmol/L)	12.6 (4.7)	14.0 (5.6)^b	14.2 (5.0)^d	<0.001
FINS (mIU/L)	11.2 (13.8)	12.6 (42.0)^a	12.2 (38.8)	0.048
2hINS (mIU/L)	38.2 (54.3)	43.0 (137.0)	44.9 (114.6)	0.194
HbA1c (%)	7.6 (1.9)	8.2 (2.1)^b	8.4 (2.0)^d	<0.001
TC (mmol/L)	4.4 (1.1)	4.6 (1.2)	4.7 (1.3)^b	0.002
TG (mmol/L)	1.3 (1.1)	1.4 (1.2)^a	1.6 (1.2)^b	0.006
LDL-C (mmol/L)	2.8 (0.851)	2.9 (0.865)	3.0 (0.910)^c	0.006
HDL-C (mmol/L)	1.2 (0.303)	1.2 (0.288)	1.1 (0.272)^c	0.050
Uric acid (mmol/L)	327.4 (89.8)	329.9 (89.4)	330.9 (85.6)	0.870

Notes: *FINS, 2hINS and TG are presented as median values with interquartile range; the other factors are presented as mean values with standard deviation. ^aSignificant difference from salt intake ≤6 g/day, P<0.05. ^bSignificant difference from salt intake ≤6 g/day, P≤0.001. ^cSignificant difference from salt intake 6–8 g/day, P<0.05. ^dSignificant difference from salt intake 6–8 g/day, P≤0.001.

Abbreviations: BMI, body mass index; WC, waist circumference; VFA, visceral fat area; SFA, subcutaneous fat area; SBP, systolic blood pressure; DBP, diastolic blood pressure; FPG, fasting plasma glucose; 2hPG, 2-hour postprandial plasma glucose; FINS, fasting plasma insulin, 2hINS, 2-hour postprandial plasma insulin; HbA_1c, glycated hemoglobin A_1c; TC, total cholesterol; TG, triglycerides; LDL-C, low-density lipoprotein cholesterol; HDL-C, high-density lipoprotein cholesterol.

Table 3 Association Between Dietary Salt Intake and Plasma Glucose

Salt Intake*	β	95% CI	P
	Fasting plasma glucose
Crude model
6–8 g/day	0.538	0.095, −0.292	0.017
>8 g/day	0.731	0.292, 1.2	0.001
Adjusted model^a
6–8 g/day	1.4	−0.442, 3.1	0.139
>8 g/day	2.3	0.472, 4.1	0.013
	2-hour postprandial plasma glucose
Crude model
6–8 g/day	1.4	0.625, 2.2	<0.001
>8 g/day	1.5	0.742, 2.3	<0.001
Adjusted model^a
6–8 g/day	2.3	−0.960, 5.6	0.166
>8 g/day	1.5	−1.8, 4.8	0.380

Notes: ≤6 g/day salt intake is the reference category in the model. ^aAdjusted for sex, age, education, physical activity, smoking, drinking, creatinine, uric acid, lipids, medication and interactions.

Abbreviations: β, beta-coefficient; CI, confidence interval.

Table 4 Association Between Dietary Salt Intake and Insulin

Salt Intake*	β	95% CI	P
	Fasting insulin
Crude model
6–8 g/day	20.3	7.7, 32.9	0.002
>8 g/day	7.5	−5.3, 20.2	0.251
Adjusted model^a
6–8 g/day	−22.7	−78.3, 32.8	0.422
>8 g/day	−0.274	−56.1, 55.5	0.992
	2-hour postprandial insulin
Crude model
6–8 g/day	47.7	19.7, 75.6	0.001
>8 g/day	22.8	−5.6, 51.1	0.116
Adjusted model^a
6–8 g/day	−73.7	−163.2, 77.6	0.229
>8 g/day	−42.8	−193.6, 46.3	0.486

Notes: ≤6 g/day salt intake is the reference category in the model. ^aAdjusted for sex, age, education, physical activity, smoking, drinking, creatinine, uric acid, lipids, medication and interactions.

Abbreviations: β, beta-coefficient; CI, confidence interval.

Table 5 Association Between Dietary Salt Intake and HbA_1c

Salt Intake^a*	β	95% CI	P
Crude model
6–8 g/day	0.43	−0.21, 1.1	0.188
>8 g/day	0.64	0.002, 1.3	0.049
Adjusted model^a
6–8 g/day	0.44	−0.18, 1.1	0.162
>8 g/day	0.67	0.04, 1.3	0.032

Notes: ≤6 g/day salt intake is the reference category in the model. ^aAdjusted for sex, age, education, physical activity, smoking, drinking, creatinine, uric acid, lipids, medication and interactions.

Abbreviations: β, beta-coefficient; CI, confidence interval; HbA_1c, glycated hemoglobin A_1c.