TABLE 1.

Metformin and placebo group characteristics at baseline (in the combined groups) and, on average, up to the time of diabetes onset or the final visit during 3.2 years of follow-up

	Baseline	Follow-up
	Metformin and placebo combined*	Placebo (change from baseline)	Metformin (change from baseline)	P
n	2,155	1,082	1,073
Weight (kg)	94.30 ± 0.43	0.29 ± 0.16	−1.72 ± 0.15†	<0.001
BMI (kg/m2)	34.02 ± 0.14	0.11 ± 0.06	−0.62 ± 0.06†	<0.001
Waist circumference (cm)	105.02 ± 0.31	−0.23 ± 0.18	−1.63 ± 0.19†	<0.001
Waist-to-hip ratio	0.9238 ± 0.0018	−0.0037 ± 0.0015	−0.0078 ± 0.0015	0.036
Fat per day (g)	82.00 ± 1.03	−11.66 ± 0.93†	−13.23 ± 0.91†	0.230
Calories per day (kcal)	2,121.21 ± 22.14	−252.36 ± 20.10†	−287.32 ± 19.83†	0.216
Percent of calories from fat	34.05 ± 0.15	−0.77 ± 0.18†	−0.84 ± 0.17†	0.783
MAQ: leisure MET h/week	16.73 ± 0.59	1.01 ± 0.54	1.26 ± 0.61†	0.751
LoPAR: recreational MET h/week	66.96 ± 0.89	2.46 ± 0.95†	1.06 ± 0.86	0.244
A1C (%)	5.91 ± 0.01	0.11 ± 0.01†	0.03 ± 0.01†	<0.001
Glucose (mmol/l)
Fasting	5.92 ± 0.01	0.13 ± 0.01†	−0.08 ± 0.01†	<0.001
30-min postload	9.44 ± 0.03	0.36 ± 0.04†	0.25 ± 0.04†	0.043
120-min postload	9.15 ± 0.02	−0.23 ± 0.06†	−0.31 ± 0.06†	0.302
Insulin (pmol/l)
Fasting	161.19 ± 1.94	6.02 ± 2.45†	−13.01 ± 2.17†	<0.001
30-min postload	606.54 ± 8.49	2.92 ± 9.34	−36.67 ± 8.32†	<0.001
Fasting proinsulin (pmol/l)	18.29 ± 0.31	0.80 ± 0.39†	−2.45 ± 0.34†	<0.001
IGR (pmol/mmol)‡	133.92 ± 2.17	−6.94 ± 3.89	−12.87 ± 2.39†	0.190

Data are means ± SE.

^*There were no significant differences (P < 0.10) between the metformin and placebo participants in any variables at baseline.

^†Mean change from baseline within a group is significantly different from zero at P < 0.05.

^‡IGR 3 (I₃₀ − I₀)/(G₃₀ − G₀) using the baseline (0) and 30-min insulin and glucose values from the OGTT. MAQ, Modifiable Activity Questionnaire; LoPAR, Low-Level Physical Activity Recall.