Characteristics of oral glucose tolerance test in 9803 pregnant women of different pre-pregnancy body mass index and its relationship with the incidence of gestational diabetes mellitus

Abstract

To investigate the values and characteristics of 75 g oral glucose tolerance test (OGTT) in women with different pre-pregnancy body mass index (BMI) and to evaluate the risk of gestational diabetes mellitus (GDM). Medical records of 9803 pregnant women attending the Peking University First Hospital and delivered between July 1, 2011 and December 31, 2013 were retrospectively analyzed. The frequency of adverse pregnancy outcomes across different degrees pre-pregnancy BMI was calculated. We divided participants into 4 groups based on pre-pregnancy BMI, underweight: BMI<18.5 kg/m(2) (1221 cases), normal weight: 18.5-23.9 kg/m(2) (6594 cases), overweight: 24-27.9 kg/m(2) (1549 cases), obesity: ≥28.0 kg/m(2) (439 cases). The diagnosis of GDM was made when any one of the values was met or exceeded in 75 g OGTT. The characteristics of 75 g OGTT and the incidence of GDM were analyzed. (1) The average age, pre-pregnancy weight, height and pre-pregnancy BMI of the participants was (30.5±3.7) years, (57.7±9.0) kg, (162.8±4.9) cm and (21.8±3.2) kg/m(2), respectively. All the values of 75 g OGTT were presented normal distribution. (2) There was statistical difference in the glucose levels among women with different pre-pregnancy BMI. The fasting, 1-hour, 2-hour glucose were (4.55±0.34), (7.31±1.54), (6.38±1.23) mmol/L in underweight women, (4.65±0.38), (7.70±1.59), (6.70±1.27) mmol/L in normal weight women, (4.82±0.47), (8.29±1.67), (7.04±1.29) mmol/L in overweight women and (4.94±0.48), (8.56±1.64), (7.10±1.35) mmol/L in obesity women (P<0.01). (3) The incidence of GDM was 21.76% (2133/9803) in our study. There were 1374 cases (64.42%, 1374/2133) with only one abnormal OGTT value while 759 cases (35.58%, 759/2133) with two or more abnormal values. The incidence of GDM in women with underweight, normal weight, overweight and obesity was 12.53% (153/1221), 19.71% (1300/6594), 32.73% (507/1549) and 39.41% (173/439), respectively (P<0.05). Meanwhile, the incidence of women with two and more abnormal OGTT value in GDM was increased as the pre-pregnancy increasing. The risk of GDM is increased as pre-pregnancy BMI increasing, and the risk of GDM increases significantly in women with pre-pregnancy overweight or obesity.