Table 2.

Estimated mean A_1c level and instantaneous linear change in A_1c at baseline and 3 and 6 months with group differences and prestudy A_1c level as a covariate.^a

Factor		n	Usual care group	Treatment group	Group difference	t-ratio159 b	P
Mean A 1c level, % (mmol/mol)
	Baseline	90	8.16 (66)	8.46 (69)	0.30	1.57	.12
	3 months	83	7.68 (60)	7.81 (62)	0.11	0.63	.53
	6 months	80	7.46 (58)	7.35 (57)	–0.11	–0.59	.55
Prestudy A1c effectc			0.52	—	—	5.23	<.001
Instantaneous linear change in A 1c d
	Baseline	90	–0.62	–0.80	–0.18	–0.94	.35
	3 months	83	–0.35	–0.56	–0.21	–1.87	.06
	6 months	80	–0.07	–0.31	–0.23	–2.87	.005
Estimated change from baseline to 6 months			–0.70	–1.11	–0.41
Acceleration ratee			0.14	0.12	–0.01	–0.26	.80

^a Tabled values are maximum-likelihood estimates.

^b t-ratios are ratios of the estimates to their respective standard errors.

^c The prestudy A_1c effect, a regression coefficient, is the change in A_1c when measured during the study for a unit increase in prestudy A_1c level.

^d Instantaneous linear change in A_1c reflects the point change in A_1c for a 90-day increment.

^e Acceleration rate is the rate of acceleration of the quadratic growth model.