The effect of smoking on the risk of gestational diabetes mellitus and the OGTT profile during pregnancy.

OBJECTIVE: To analyze the relationship between smoking and the risk of GDM, as well as with the OGTT profile during pregnancy. PATIENTS AND METHODS: A total of 7437 pregnant women were studied. OGTT was performed at the 3rd trimester. Women were categorized as non-smokers (A), as those who ceased smoking at pregnancy (B), and as smokers (C). RESULTS: 5434 (73.1%) women were group A, 1191 (16%) group B and 812 (10.9%) group C. The rates of GDM among the groups were: A 33.7%, B 34.2%, C 34.2% (ns). However, the number of individuals requiring insulin treatment was significantly different: A 39.2%, B 47.5%, C 50.6% (p < 0.001). Regarding OGTT, fasting glucose levels were significantly higher in group C (89 ±â€¯13 vs 86 ±â€¯12 mg/dl) compared to A, whereas 3-h glucose values were significantly lower (104 ±â€¯33 vs 112 ±â€¯32 mg/dl) (p < 0.001). Group B demonstrated intermediate glucose concentrations. Similar findings were observed in women without GDM. In women with GDM, higher 1-h glucose levels were measured in group C (210 ±â€¯31 vs 205 ±â€¯28 mg/dl) compared with A (p = 0.024). Further, group C sub-analysis found that those who smoked more than 10 cigarettes showed significantly lower 3-h glucose levels (111 ±â€¯31 vs 128 ±â€¯40 mg/dl) compared to those who smoked less than 10 (p = 0.006). HbA1c in women with GDM was higher in group C (4.6 ±â€¯0.6 vs 4.5 ±â€¯0.6%) compared with A (p = 0.027). CONCLUSIONS: The present study did not show any correlation between smoking and GDM risk. However, OGTT profile and HbA1c differed according to smoking status in women with and without GDM.