Table 4.

Cox regression models estimating hazard ratios for baseline body fat composition variables predicting diabetes by treatment group in women

	Placebo (n = 738)					Metformin (n = 701)					Lifestyle (n = 727)
Baseline variable	% R2	c-index*	HR	95% CI	p	% R2	c-index*	HR	95% CI	p	% R2	c-index*	HR	95% CI	p
Waist circumference (cm)	2.23	0.597a	1.29	(1.11–1.50)	<0.01	0.62	0.561	1.07	(0.90–1.29)	0.43	2.87	0.637a	1.53	(1.27–1.85)	<0.01
Waist-to-height ratio	2.05	0.594	1.27	(1.09–1.47)	<0.01	0.78	0.574	1.12	(0.95–1.34)	0.18	2.05	0.628b	1.41	(1.17–1.70)	<0.01
Waist-to-hip ratio	1.92	0.591	1.27	(1.08–1.48)	<0.01	0.71	0.567	1.10	(0.93–1.29)	0.26	2.28	0.621	1.44	(1.20–1.74)	<0.01
Subscapular skinfold† (cm)	1.67	0.581	1.22	(1.05–1.42)	<0.01	0.53	0.553	0.99	(0.83–1.19)	0.93	1.30	0.592	1.30	(1.08–1.57)	<0.01
Suprailiac skinfold (cm)	1.58	0.583	1.20	(1.04–1.38)	0.01	0.54	0.553	1.02	(0.85–1.22)	0.86	0.54	0.565	1.14	(0.94–1.38)	0.19
BMI† (kg/m2)	1.56	0.583	1.20	(1.04–1.39)	0.01	0.56	0.554	0.96	(0.80–1.15)	0.67	2.12	0.631c	1.42	(1.18–1.70)	<0.01
Weight† (kg)	1.54	0.584	1.18	(1.04–1.35)	0.01	0.80	0.567	0.87	(0.71–1.07)	0.18	3.18	0.639d	1.59	(1.32–1.93)	<0.01
Sum of skinfolds excluding calf† (cm)	1.51	0.578	1.19	(1.03–1.38)	0.02	0.54	0.555	0.97	(0.81–1.16)	0.76	0.79	0.573	1.20	(0.99–1.46)	0.06
Sum of skinfolds† (cm)	1.38	0.577	1.18	(1.01–1.36)	0.03	0.55	0.556	0.97	(0.81–1.16)	0.71	0.74	0.573	1.19	(0.98–1.45)	0.07
Hip circumference (cm)	1.29	0.568a	1.16	(1.00–1.35)	0.05	0.53	0.554	0.99	(0.83–1.19)	0.94	1.13	0.583a–d	1.27	(1.05–1.54)	0.01
Triceps + subscapular (cm)	1.28	0.574	1.16	(1.00–1.34)	0.05	0.53	0.553	0.99	(0.82–1.18)	0.87	1.01	0.585	1.25	(1.03–1.51)	0.02
Abdominal skinfold (cm)	1.23	0.567	1.15	(0.99–1.33)	0.06	0.61	0.564	0.93	(0.78–1.11)	0.45	0.48	0.558	1.12	(0.92–1.36)	0.27
Triceps skinfold (cm)	0.90	0.558	1.08	(0.93–1.25)	0.33	0.54	0.553	0.98	(0.82–1.17)	0.83	0.56	0.566	1.15	(0.94–1.39)	0.17
Calf skinfold (cm)	0.81	0.553	1.05	(0.90–1.20)	0.55	0.56	0.555	0.96	(0.81–1.14)	0.63	0.40	0.553	1.08	(0.89–1.31)	0.42

Ordered by magnitude of R² ratio in placebo group; HRs are 1 unit per standard deviation. All models are adjusted for age and self-reported race/ethnicity. HR, hazard ratio; CI, confidence interval.

^*Equal superscripts (a– d) within treatment group on the c-index indicate measurements that are significantly different from each other at p = 0.05. For example, in the lifestyle group, the c-index for waist circumference is significantly greater than the c-index for hip circumference.

^†Significant interaction between body fat measurement and treatment group (p ≤ 0.05).