Gestational diabetes mellitus (GDM) seriously threatens the health of mothers as well as infants, and its occurrence is increasing year by year . Identifying groups at high risk of GDM in the early stages of pregnancy, and taking active measures to reduce its occurrence and associated complications is a current concern. The HTWC phenotype is a clinical phenotype that combines biochemical and anthropometric indices. Previous results have shown that the risk of DM significantly increases in those with the HTWC phenotype, and that this information can be used to predict the likelihood of DM occurring [6, 7, 8]. Therefore, in this study, the relationship between HTWC and GDM was explored, and the risk factors for GDM were analysed to find a theoretical basis for its early prevention and treatment.
This study found several indices for metabolic abnormalities in pregnant women with the HTWC phenotype, and these were significantly higher than in other groups. These include indices for abnormal glucose metabolism (e.g. OGTT 0 h, 1 h and 2 h blood glucose, AUCG, increased glycated haemoglobin and HOMA-B changes), and indices for abnormal lipid metabolism (e.g. lower HDL-C and higher LDL-C, TG, and TC levels). Insulin resistance related indices showed increased levels of HOMA-IR and UA. This suggested that pregnant women with the HTWC phenotype had multiple risk factors for DM, and their risk of GDM was also significantly increased. This study found that the occurrence of GDM in the HTWC phenotype group was significantly higher than in the other three groups (P < 0.001). Multivariate logistic regression showed that the prevalence of GDM in the HTWC group was 3.779 times higher than in group A (both TG and waist circumference were normal) with 95% CI 2.163–6.602. After adjusting many risk factors by multivariate logistic regression analysis, the prevalence of GDM in the HTWC phenotype group was still 1.753 times higher than in the normal group (95% CI 1.238–2.483). Previous studies have shown that the HTWC phenotype represents an aggregation of multiple metabolic abnormalities. This can be used to screen the population who are at high risk of GDM, and has a significant ability to predict the onset of GDM .
GDM leads to adverse pregnancy outcomes , and the long-term prognosis for women and children affected by it is poor. The risk of developing Type 2 diabetes mellitus in future is more than 7 times higher than that of the general population . GDM has attracted a lot of attention from endocrinologists and obstetricians, and there are also an increasing number of studies regarding its pathogenesis. At present, it is generally believed that the occurrence of GDM is related to increased insulin resistance. During pregnancy, the secretion of a variety of hormones with insulin antagonism increases, resulting in decreased sensitivity of the surrounding tissues to insulin, producing insulin resistance (IR). IR has a significant effect on the glucose metabolism of pregnant women and is characterised by decreased glucose uptake and utilisation, as well as a gradual increase in blood glucose. Wang et al. have shown that untreated GDM patients had more severe IR than normal pregnant women during the first, second and third trimesters. Waist circumference was considered as a predictor of abdominal obesity , and elevated TG was an early manifestation of IR . Therefore, HTWC leads to IR , and increases the risk of GDM. However, the prevalence of simple abdominal obesity and simple hypertriglycemia in GDM patients is lower than in HTWC patients. In this study, the prevalence of GDM in groups A, B and C was significantly lower than in group D. Therefore, combining waist circumference and TG improved the ability to detect early GDM. The occurrence of GDM in women in the early stages of pregnancy, with the HTWC phenotype, was more prevalent than in the other groups. Early detection of the HTWC phenotype and active intervention in the development of obesity and abnormal lipid metabolism could effectively reduce the risk of GDM.
This study found that FINS in the HTWC group was higher than in the other groups, and HOMA-β was higher than in group A. The reason for this might be that due to IR increasing during pregnancy, the function of islet β cells was enhanced to compensate. This enhancement is mainly due to increased basal insulin secretion, but is not enough to overcome the gradually increasing IR, and so results in increased blood glucose levels after fasting and glucose load during all stages. Paradisi et al.  also found that fasting insulin was increased by 37.5% in the third trimester of pregnancy when compared with the second trimester of pregnancy. Wang et al.  found that HOMA-β values during the first, second and third trimesters of pregnancy in the group with GDM were higher than in the corresponding control group, indicating that the function of islet β cells in GDM patients was slightly impaired but still had compensatory ability. Although the postpartum blood glucose levels in these groups can return to normal levels, the risk of postpartum Type 2 diabetes was increased due to IR and mild impairment of islet β cell function [16–18], indicating that IR in pregnant women gradually increased from the first trimester to the third trimester of pregnancy, and insulin sensitivity gradually decreased. However, this study only observed the islet β cell function index and IR index during the second trimester of pregnancy. It would be more useful to comprehensively analyse the development of IR in GDM, and the relationship between insulin resistance and the onset of GDM, if the data for islet function in the first and third trimesters of pregnancy were available.
This study found that people with the HTWC phenotype had more abnormal indices of glycolipid metabolism, insulin secretion and IR than those in the normal group, simple high triglyceride group and simple abdominal obesity group. Also, the occurrence of GDM in women with the HTWC phenotype was higher than in the other three groups, indicating that the risk of GDM in this group was higher. This suggested that the occurrence and development of GDM might be affected by obesity, IR and other effects.
In conclusion, this is a preliminary study that explored the value of the HTWC phenotype in screening for GDM. The results showed that the HTWC phenotype significantly increased the risk of GDM and independently predicted the risk of GDM occurring. However, these findings need further clarification, so in future studies a larger sample size would be useful. The measurement of waist circumference and TG is simple and inexpensive. When screening for GDM, if the HTWC phenotype can be used for early detection and control, the risk can be effectively reduced and the health of mothers as well as infants can be protected.
However, there were certain limitations in the current study. First, this study used a cross-sectional design, limiting our ability to conclusively prove the results. Second, BMI 1 was self-reported by the subjects without being independently measured by professionals. Finally, although the results were adjusted for many variables, there may be others (such as dietary habits and physical exercise) that were not allowed for.