Table 1.

Baseline characteristics of participants in the type 2 diabetes case-control study with repeated metabolomics profiles, nested within the Nurses' Health Study.

	First metabolomics profile [1990]		Second metabolomics profile [2000]		Change [2000 vs. 1990]*
	Controls [n=248]	Cases [n=248]	Controls [n=244]#	Cases [n=244]	ΔControls	ΔCases
Age [years]	54.0§ (49.3, 58.7)	53.9 (49.5, 58.7)	65.3 (60.4, 69.8)	64.8 (60.3, 70)	11.2 (10.9-11.4)	11.2 (10.8-11.4)
Body mass index [kg/m2]	24.0 (22.0, 26.8)	26.7 (23.9, 29.9)	25.9 (22.7, 29.1)	28.8 (25.5, 33.1)	1.2 (0.0-2.4)	1.8 (0.4-3.5)
Physical activity [METS-h/week]	9.1 (3.1, 21.3)	8.4 (2.5, 21.6)	12.9 (5.1, 21.5)	10.2 (3.6, 23.2)	2.1 (-5.0-10.0)	0 (-5.1-8.0)
Diet quality (AHEI)|	52.4 (46.8, 59.5)	51.0 (43.6, 58.4)	53.9 (46.5, 60.5)	50.2 (44.2, 58.1)	0.3 (-5.1-6.5)	-0.1 (-5.5-5.7)
Alcohol [g/day]	1.3 (0.0, 5.5)	0.9 (0.0, 3.7)	1.5 (0.0, 6.3)	0.9 (0.0, 5.2)	0 0.(-0.8, 1.1)	0.0 (0.0, 0.9)
Smoking
Current	13%	12%	6%	5%	-7%	-7%
Former	35%	40%	42%	46%	7%	6%
Never	52%	47%	52%	48%	0	1%$
Family history of T2D (one or more prevalent T2D case among parents and siblings)
Yes	25%	40%	-	-	-	-

Controls: women without incident type 2 diabetes during follow-up.

Cases: women with incident type 2 diabetes during follow-up.

^⁎Change in participant characteristics between first (1989/90) and second (2000/01) blood collection. Covariable changes: Body mass index, 2000 vs. 1990; Alternative Healthy Eating Index (AHEI), 1998 vs. 1990, METS, 2000 vs. 1988; smoking status, 2000 vs. 1990.

^#Four case-control pairs were without valid metabolomics data for the second time point and excluded from all analyses that included the second metabolomics profile.

^§Median (IQR), all such values.

^|Diet quality was measured with the Alternative Healthy Eating Index (AHEI).

^$Higher proportion of Never Smokers due to the exclusion of four case-control pairs.