Table A3.

Beta coefficients for FLOX^ICE and FC mix algorithms.

	Beta Coefficients (95% CI) p-Value
	Plasma Glucose	Delay	Delay^2	Constant
FLOXICE algorithm
Fasting PG	0.999	0.108	−0.004	0.125
	(0.966–1.032) p < 0.001	(0.093–0.122) p < 0.001	(−0.004–(−)0.003) p < 0.001	(−0.034–0.283) p = 0.122
1-h PG	0.981	0.107	−0.004	0.279
	(0.961–1.000) p < 0.001	(0.074–0.139) p < 0.001	(−0.005–(−)0.002) p < 0.001	(0.140–0.419) p < 0.001
2-h PG	0.949	0.091	−0.003	0.426
	(0.919–0.979) p < 0.001	(0.055–0.127) p < 0.001	(−)0.002) p < 0.001	(0.243–0.610) p < 0.001
FC mix algorithm
Fasting PG	0.986	0.106	−0.004	0.386
	(0.953–1.019) p < 0.001	(0.091–0.121) p < 0.001	(−0.004–(−)0.003) p < 0.001	(0.227–0.545) p < 0.001
1-h PG	1.043	0.112	−0.004	0.146
	(1.015–1.071) p < 0.001	(0.066–0.158) p < 0.001	(−0.006–(−)0.002) p < 0.001	(−0.055–0.347) p = 0.154
2-h PG	1.098	0.105	−0.004	−0.182
	(1.075–1.120) p < 0.001	(0.078–0.132) p < 0.001	(−0.005–(−)0.003) p < 0.001	(−0.321–(−)0.044) p = 0.01

FLOX = fluoride-oxalate; FC Mix = fluoride-citrate-EDTA. To generate algorithms to adjust OGTT results for estimated glycolysis due to delay to analysis, 12 participants in a hospital setting had paired samples collected alongside their standard OGTT (1-h and 2-h samples, n = 11): FLOX^RT protocol: FLOX tube (5 mL BD Biosciences, Australia) stored at room temperature (RT). Aliquots collected at 0.25 h, 0.5 h, 0.75 h, 1 h, 1.5 h, 2 h, 2.5 h, 3 h, 3.5 h, and 4 h. FLOX^ICE protocol: FLOX tube (2 mL BD Biosciences, Australia) placed immediately in ice-slurry. Aliquots collected at 0.25 h, 0.5 h, 0.75 h, 1 h, and 4 h. FC Mix protocol: FC Mix tube (3 mL Greiner Bio-One, Austria) stored at RT. Aliquots collected at 0.25 h, 0.5 h, 0.75 h, 1 h, and 4 h. Following 4 h incubation, FLOX^RT, FC Mix and PST tubes from six participants were refrigerated overnight for 24 h PG analysis. Whole blood aliquots (300 μL) were centrifuged at 1300× g for 5 min and 100 μL of plasma removed for plasma glucose (PG) analysis. Baseline FLOX^ICE glucose was calculated as mean FLOX^ICE glucose from plasma separated < 1 h post-collection. Baseline FC Mix glucose was calculated as mean FC Mix glucose from plasma separated ≤ 4 h. Beta coefficients were calculated by linear regression for FLOX^RT PG, delay, and delay-squared to estimate baseline FLOX^ICE or baseline FC Mix.