Table 2.

Measures of β-cell secretory capacity, β-cell sensitivity to glucose, insulin sensitivity, and glucagon secretion derived from the GPA test

	Exenatide (n = 14)			Sitagliptin (n = 12)			Glimepiride (n = 14)
	Baseline	6 monthsa	Δ	Baseline	6 monthsa	Δ	Baseline	6 monthsa	Δ
AIRarg (μU/mL)	52 ± 14	52 ± 11	−0.2 ± 9	35 ± 4	34 ± 6	−2 ± 7	44 ± 6	42 ± 4	−2 ± 7
AIRpot (μU/mL)	138 ± 31	108 ± 21	−30 ± 20†	83 ± 12	80 ± 15	−2 ± 8	97 ± 16	119 ± 19	22 ± 12
AIRmax (μU/mL)	214 ± 60	188 ± 34	−25 ± 50‡	149 ± 20	158 ± 30	9 ± 21	133 ± 19	202 ± 35*	69 ± 33
PG50 (mg/dL)	175 ± 13	190 ± 14	25 ± 20	226 ± 12	209 ± 16	−5 ± 24	168 ± 17	182 ± 10	10 ± 26
M (mg · kg−1 · min−1)	5.5 ± 0.3	5.8 ± 0.4	0.27 ± 0.4	5.4 ± 0.4	5.3 ± 0.4	−0.1 ± 0.4	5.5 ± 0.4	5.8 ± 0.4	0.35 ± 0.4
I (μU/mL)	41 ± 13	39 ± 9	−2 ± 9	22 ± 2	23 ± 4	1 ± 3	28 ± 7	26 ± 2	−2 ± 5
M/I (mg · kg−1 · min−1/μU/mL)	0.3 ± 0.1	0.3 ± 0.1	−0.01 ± 0.0	0.3 ± 0.0	0.3 ± 0.1	0.04 ± 0.1	0.3 ± 0.1	0.3 ± 0.1	−0.04 ± 0.0
AGRarg (pg/mL)	60 ± 12	63 ± 8	3 ± 17	77 ± 13	60 ± 11	−17 ± 6	40 ± 9	62 ± 8	22 ± 17
AGRinh (pg/mL)	63 ± 12	58 ± 13	−3 ± 6	64 ± 13	55 ± 16	−10 ± 10	46 ± 7	59 ± 7	11 ± 7
AGRmin (pg/mL)	51 ± 12	52 ± 12	2 ± 5‡	55 ± 8	59 ± 19	4 ± 21	37 ± 6	59 ± 8*	21 ± 8

Data are means ± SE.

Δ, change from baseline to 6 months with each value.

^aFinal visits after 6 months of therapy were conducted following a 5- to 7-day drug washout.

*P < 0.05 when comparing values within each group.

†P < 0.05 when comparing Δ between the exenatide and glimepiride groups.

‡P ≤ 0.1 (statistical trend) when comparing Δ between exenatide and glimepiride groups.