Salivary glucose concentration exhibits threshold kinetics in normal-weight, overweight, and obese children

Figures & data

Table 1 Within- and between-day CV measurements of glucose in saliva samples

Glucose concentration (mg/dL)	Within-day CVa	Between-day CVb
≥0.2	22.9	27.3
0.2< concentration >0.1	54.6	41.0
≤0.1	101.1	46.1

Notes:

a Duplicate measurements on one day (18 samples)

b three measurements over 98 days (47 samples).

Abbreviation: CV, coefficient of variation.

Table 2 Population characteristics of the enrolled children

	Body weight category				Overall
	Underweight	Normal weight	Overweight	Obese
N	2	30	12	21	65
Age (y)	9.8±1.4	10.0±0.2^a	11.2±0.5	11.2±0.4^a	10.6±0.2*
Sex (number of males [%])	1 (50)	18 (60)	7 (58.3)	15 (71.4)	41 (63.0)
Plasma glucose (mg/dL)	89.5±10.5	86.5±1.2	84.8±1.9	86.5±1.5	86.3±0.8
Salivary glucose (mg/dL)	0.29±0.04	0.10±0.02	0.11±0.03	0.09±0.04	0.11±0.02
Glucose excretion (μg/h)	88.1±20.4	42.6±10.9	54.3±24.6	27.9±13.7	41.2±8.0
Saliva flow rate (mL/h)	29.6±2.6	40.5±3.4	44.2±5.5	38.3±4.8	40.1±2.4
Diastolic blood pressure (mmHg)	69±2	67±1	68±2	69±2	69±1
Systolic blood pressure (mmHg)	119±2	116±2	121±3	124±2	120±1
BMI	13.5±0.3^ab	17.2±0.3^cd	22.2±0.6^ace	28.5±1.2^bde	21.7±0.8*

Notes:

* Model P<0.05. Tabulated ranges are mean ± SEM. Overall differences between body weight categories were tested by ANOVA. Significant pairwise differences were determined by post hoc analysis using Tukey’s test. Values with the same superscript letter within each row differed at P<0.05.

Abbreviations: ANOVA, analysis of variance; BMI, body mass index; SEM, standard error of the mean.

Figure 1 Saliva glucose concentration (Sg) as a function of salivary flow rate (F) by regression analysis.

Figure 2 Plasma glucose concentration as a function of salivary glucose concentration.

Notes: (A) Regression analysis of samples from all of the children in the study (mean age 10.6±0.2 y). (B) 2×2 analysis of the diagnostic capability of salivary glucose testing to identify children with high plasma glucose levels (>90 mg/dL) using a value of 0.06 mg/dL in saliva as an identification criterion. (C) Receiver operating curve indicating an area AUC measurement of 0.78.
Abbreviations: TP, true positive (red); FP, false positive (green); TN, true negative (black), FN, false negative (blue); PPV, positive predictive value; NPV, negative predictive value; AUC, area under the curve.

Table 3 Representative studies that provide analytical data for evaluating the relationship between salivary glucose and blood glucose concentrations as a threshold response

Study	Species	Sample	Threshold (mg/dL)	Slope	r	P-value	Population
Forbat et al (1981)^Citation25	Human	Parotid salivaa	136.8	6.4	0.20	0.38	20 diabetic adultsb
Amer et al (2001)^Citation15	Human	Whole saliva	107.0	12.7	0.78	<0.05	135 diabetic adults
Abikshyeet et al (2012)^Citation14	Human	Whole saliva	99.7	13.0	0.77	<0.01	106 diabetic adults
Current study	Human	Whole saliva	84.8	13.5	0.33	0.006	65, 11-year-old children
Yamaguchi et al (1998)^Citation26
A	Human	Submaxillary +	110	22.4			6 healthy adults (A–F)c
B		sublingual saliva	68	87.1
C			104	13.8
D			60	111.1
E			105	46.7
F			88	51.0
Average			89.1±8.6	55.3±15.3
Hayford et al (1983)^Citation27	Human	Urine	152.7	47.4	0.80		24 diabetic adults
Langley et al (1958)^Citation24	Dogs	Parotid saliva	512.0				10–12 kg dogs

Notes: One study of urine glucose concentration is also included for comparison.

a Stimulated with lemon juice and parotid massage

b 50 μL samples only

c 75 g oral glucose tolerance test.

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