Table 2.

Socioeconomic Factors in Relation to Incidence of Type 2 Diabetes in the Black Women's Health Study, United States, 1995–2007

	No. of Cases	No. of Person-Years	IRR	95% CIa	IRR	95% CIb	IRR	95% CIc
Participant's education, years
≤12	937	74,778	1.28	1.15, 1.43	1.24	1.11, 1.39	1.20	1.08, 1.35
13–15	1,393	146,588	1.21	1.09, 1.33	1.19	1.08, 1.32	1.14	1.04, 1.27
16	747	104,075	1.05	0.95, 1.17	1.06	0.95, 1.18	1.07	0.96, 1.19
≥17	750	99,816	1.0		1.0		1.0
Ptrend			<0.0001		<0.0001		0.0002
Participant's household income, $
<15,000	231	16,038	1.57	1.30, 1.90	1.43	1.18, 1.73	1.20	0.99, 1.47
15,001–25,000	301	25,474	1.27	1.07, 1.52	1.16	0.98, 1.39	1.06	0.89, 1.27
25,001–35,000	447	38,360	1.42	1.21, 1.67	1.34	1.14, 1.57	1.24	1.05, 1.45
35,001–50,000	673	70,686	1.31	1.14, 1.51	1.23	1.07, 1.42	1.16	1.00, 1.34
50,001–100,000	1,151	142,632	1.24	1.10, 1.41	1.20	1.06, 1.35	1.14	1.01, 1.29
>100,000	352	65,049	1.0		1.0		1.0
Ptrend			<0.0001		0.0008		0.09
Neighborhood SES score
Quintile 1 (lowest SES)	1,015	82,362	1.65	1.46, 1.85	1.48	1.32, 1.67	1.26	1.12, 1.42
Quintile 2	796	80,876	1.40	1.25, 1.58	1.29	1.15, 1.45	1.18	1.05, 1.33
Quintile 3	766	83,226	1.38	1.23, 1.55	1.29	1.15, 1.45	1.21	1.08, 1.36
Quintile 4	704	89,525	1.22	1.08, 1.36	1.18	1.05, 1.32	1.12	1.00, 1.26
Quintile 5 (highest SES)	552	89,776	1.0		1.0		1.0
Ptrend			<0.0001		<0.0001		<0.0001

Abbreviations: CI, confidence interval; IRR, incidence rate ratio; SES, socioeconomic status.

^aModel 1: adjusted for age, time period, individual SES variables (education, household income, household size, and marital status), and neighborhood SES.

^bModel 2: adjusted for all variables in model 1 plus family history of diabetes, smoking, alcohol intake, energy intake, vigorous activity, and female hormone use.

^cModel 3: adjusted for all variables in model 2 plus body mass index.