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 +/- 13 vs 86 +/- 12 mg/dl) compared to A, whereas 3-h glucose values were significantly lower (104 +/- 33 vs 112 +/- 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 +/- 31 vs 205 +/- 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 +/- 31 vs 128 +/- 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 +/- 0.6 vs 4.5 +/- 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. (C) 2019 Elsevier B.V. All rights reserved.