TABLE 3.

Glucose metabolism, insulin secretion, and β cell function¹

Glucose metabolism and insulin kinetics	LoGIX		HiGIX		P (2-factor ANOVA)
	Prestudy	Poststudy	Prestudy	Poststudy	Time	Trial	Time × trial
Basal Ra (mg · kg−1 · min−1)	2.43 ± 0.57	1.52 ± 0.07	2.60 ± 0.27	1.43 ± 0.12	0.005	0.51	0.69
Insulin Ra (percentage suppression)	52.7 ± 5.9	76.6 ± 7.2	33.6 ± 9.0	63.5 ± 11.4	0.002	0.22	0.68
Insulin Rd (mg · kg−1 · min−1)	2.22 ± 0.26	4.12 ± 0.40	3.12 ± 0.40	4.60 ± 0.59	<0.0001	0.31	0.42
Insulin Rd (mg · kg−1 FFM · min−1)	4.41 ± 0.56	7.48 ± 0.80	5.48 ± 0.75	7.75 ± 0.96	<0.0001	0.31	0.39
Basal ISR (nmol/min)	2.86 ± 0.49	1.87 ± 0.31	1.80 ± 0.23	1.45 ± 0.15*	0.0004	0.02	0.05
OGTT ISRauc (nmol)	6.59 ± 0.86	4.70 ± 0.67	4.40 ± 0.55	4.25 ± 0.66	0.01	0.02	0.02
ISR/G (au)	8.28 ± 0.91	6.41 ± 0.89	6.01 ± 0.72	5.65 ± 0.64*	0.02	0.07	0.09
ISR/G ÷ IR (au)	31.5 ± 4.1	32.6 ± 4.3	26.8 ± 3.0	37.3 ± 3.3*	0.01	0.03	0.04

¹All values are means ± SEMs (n = 22). LoGIX, low–glycemic index diet; HiGIX, high–glycemic index diet; Basal R_a, rate of appearance of plasma glucose during fasting conditions; Insulin R_a, insulin-stimulated rate of appearance of plasma glucose; R_d, insulin-stimulated rate of disappearance of plasma glucose; FFM, fat-free mass; Basal ISR, insulin secretion rate during fasting conditions; OGTT ISR_auc, total area under the insulin secretion rate curve after ingestion of 75 g glucose (oral-glucose-tolerance test ); ISR/G, insulin secretory response to OGTT divided by the plasma glucose response; ISR/G ÷ IR, insulin secretory response to OGTT corrected for changes in insulin resistance; au, arbitrary units. After the study, both groups showed significant improvements in insulin sensitivity, whereas only the LoGIX group showed improvement in insulin secretion. *Group differences between poststudy values, P < 0.05. With the exception of basal ISR (P = 0.05), no between-group prestudy differences were observed (all P > 0.05, unpaired t test).