INS and gestational diabetes: In current smokers, a long duration of smoking was associated with a higher OR of insulin-requiring GDM; the ORs (95% CIs) were 1.38 (0.82–2.30) and 1.78 (1.45–2.19) for women who smoked cigarettes for < 5 years and ≥ 5 years, respectively (Table 2).