Table 2.

Adjusted odd ratios and 95% confidence intervals of gestational diabetes mellitus requiring insulin therapy by smoking status, amount and duration.

	n (%)	Events (n)	Incidence ratea	Model 1	Model 2
Smoking status
Nonsmoker	300,126 (92.3)	1,795	6.0	1 (ref.)	1 (ref.)
Former smoker	12,174 (3.7)	143	11.7	1.83 (1.54, 2.18)	1.55 (1.27, 1.90)
Current smoker	12,997 (4.0)	176	13.5	2.36 (2.01, 2.77)	1.73 (1.42, 2.09)
Amount of smoking (no. of cigarettes smoked per day)
Nonsmoker	300,126 (92.3)	1,795	6.0	1 (ref.)	1 (ref.)
Former smoker
< 15	11,454 (3.5)	127	11.1	1.75 (1.46, 2.11)	1.49 (1.21, 1.84)
≥ 15	720 (0.2)	16	22.2	2.93 (1.77, 4.85)	2.42 (1.36, 4.31)
Current smoker
< 15	11,736 (3.6)	150	12.8	2.26 (1.90, 2.68)	1.65 (1.35, 2.03)
≥ 15	1,261 (0.4)	26	20.6	3.27 (2.19, 4.88)	2.35 (1.46, 3.79)
Duration of smoking (years)
Nonsmoker	300,268 (92.3)	1,797	6.0	1 (ref.)	1 (ref.)
Former smoker
< 5	4,816 (1.5)	50	10.4	1.93 (1.45, 2.56)	1.60 (1.14, 2.23)
≥ 5	7,265 (2.2)	92	12.7	1.78 (1.43, 2.21)	1.53 (1.20, 1.95)
Current smoker
< 5	2,347 (0.7)	19	8.1	1.84 (1.16, 2.90)	1.38 (0.82, 2.30)
≥ 5	10,601 (3.3)	156	14.7	2.43 (2.05, 2.89)	1.78 (1.45, 2.19)
Amount × duration of smoking (pack-years)
Nonsmoker	300,126 (92.3)	1,795	6.0	1 (ref.)	1 (ref.)
≤ 2	13,625 (4.2)	139	10.2	1.86 (1.56, 2.21)	1.50 (1.22, 1.84)
2 <, ≤ 4	6,210 (1.9)	81	13.0	2.21 (1.76, 2.77)	1.71 (1.31, 2.22)
4 <, ≤ 6	3,222 (2.0)	49	15.2	2.23 (1.67, 2.98)	1.60 (1.13, 2.26)
6 <, ≤ 8	1,085 (0.3)	18	16.6	2.20 (1.37, 3.53)	1.97 (1.14, 3.40)
8 <, ≤ 10	568 (0.2)	16	28.2	2.97 (1.76, 5.00)	2.34 (1.22, 4.51)
> 10	461 (0.1)	16	34.7	3.27 (1.96, 5.45)	2.29 (1.25, 4.22)

Model 1: Adjusted for age, alcohol drinking, regular exercise, and income status.

Model 2: Adjusted for model 1 + body mass index, fasting blood glucose, family history of diabetes, and dyslipidemia.

^aPer 1,000 person-years.