Table 2 Odds ratios for type 2 diabetes according to different exposure metrics of night shift work

Rotating night shift work

 Never

105 (23.3)

32 (12.7)

1.00 (ref)

1.00 (ref)

 Yes

346 (76.7)

219 (87.3)

2.08 (1.35–3.19)

2.00 (1.28–3.11)

Current shift status

 Never

105 (23.2)

32 (12.7)

1.00 (ref)

1.00 (ref)

 Ever

124 (27.5)

69 (27.5)

1.83 (1.12–2.99)

1.86 (1.12–3.08)

 Current

222 (49.3)

150 (59.8)

2.22 (1.42–3.47)

2.08 (1.31–3.30)

Duration of night shifts (years)

 Never

105 (23.2)

32 (12.7)

1.00 (ref)

1.00 (ref)

 1–10

99 (22.0)

49 (19.5)

1.62 (0.96–2.74)

1.80 (1.04–3.12)

 10–20

77 (17.1)

47 (18.7)

2.00 (1.17–3.43)

2.30 (1.31–4.04)

 20–30

118 (26.2)

87 (34.8)

2.42 (1.49–3.92)

2.23 (1.35–3.67)

 > 30

52 (11.5)

36 (14.3)

2.27 (1.27–4.06)

1.51(0.82–2.80)

OR (95% CI) for trend

1.24 (1.10–1.39)

1.15 (1.01–1.30)

Average frequency of night shifts (nights/month)

 Never

105 (23.2)

32 (12.7)

1.00 (ref)

1.00 (ref)

 < 3

115 (25.5)

62 (24.7)

1.77(1.07–2.92)

1.64 (0.97–2.76)

 3–8

206 (45.8)

134 (53.4)

2.13 (1.36–3.35)

2.10 (1.32–3.34)

  > 8

25 (5.5)

23 (9.2)

3.02 (1.51–6.02)

2.72 (1.33–5.57)

OR (95% CI) for trend

1.41 (1.17–1.69)

1.39 (1.15–1.68)