4. Discussion
gestational diabetes, cardiovascular diseases, decreased fasting blood glucose, hypoglycemia, GDM, shoulder dystocia
GESTATIONAL DIABETES, CARDIOVASCULAR DISEASES, DYSFUNCTION, GDM, HYPOGLYCEMIA, INSULIN RESISTANCE, TYPE 2 DIABETES, PATHOGENESIS, COMPLICATIONS, SHOULDER DYSTOCIA
In our randomized controlled trial of women diagnosed with GDM, we demonstrated that dietary counseling focused on the addition of whole berries and leafy vegetables resulted in multiple improvements in dietary profiles and markers of cardiometabolic risks in the mother. Importantly, the baseline characteristics of each treatment group were not significantly different from one another. Additionally, daily exercise did not significantly differ between the control and intervention groups after the 12-week intervention period despite the intervention group being instructed to increase their daily postprandial physical activity. Therefore, it can be inferred that all the significant differences elucidated in this trial are due to the dietary interventions that the intervention group were instructed to begin and follow. The implementation of the USDA dietary guidelines-based nutrition education is quite ethical as a control treatment for these high-risk women as part of standard prenatal care. Thus, the significant outcomes observed in the nutrition intervention group clearly shows the effectiveness of evidence-based food group-specific counseling in improving cardiometabolic profiles in GDM. Diets rich in fruits and vegetables have been shown to improve gestational diabetes risks, as well as its management in observational studies and RCTs [In addition, total dietary flavonoid intake was also significantly different between the two groups, with the nutrition intervention group consuming an average 62 ± 16 mg/day total flavonoid intake and the nutrition education group consuming an average 45 ± 14 mg/day total intake. Flavonoids are metabolically active compounds found in a wide range of plant-based foods, including berries and vegetables, that are known for their anti-inflammatory and antioxidant functions. Specifically, flavonoids inhibit the synthesis and function of various pro-inflammatory mediators via multiple mechanisms, one of which is the inhibition of the transcription factor NF-kappaB; however, large concentrations of flavonoids are needed to exert a physiological effect [As discussed earlier, most studies on dietary habits and GDM often analyze the dietary habits and the risk of developing GDM; few studies investigate these same dietary changes during pregnancy in an already diagnosed GDM patient. The observational study by Sun et al. (2022) demonstrates that fruit intake in the first trimester directly affects blood glucose metabolism and results in a decreased fasting blood glucose level as well as a decreased risk of developing GDM in the second trimester [The average HDL-cholesterol (HDL-C) in the intervention group was significantly higher at study end at 51 ± 7 mg/dL as compared to the control group’s HDL-cholesterol at 43 ± 8 mg/dL. HDL-cholesterol, often referred to as the ‘good cholesterol’, is important for transport of cholesterol back to the liver for processing, thus lowering total circulating cholesterol [The nutrition intervention group had a significantly lower average serum IL-6 at 26 ± 3.8 pg/mL compared to the 34.6 ± 12.2 pg/mL average in the control group in our study. IL-6 is a cytokine that has been implicated in the pathogenesis of GDM via its pro-inflammatory impact on endothelium dysfunction and insulin resistance, suggesting that high levels of IL-6 are correlated with increased insulin resistance, leading to potentially higher blood glucose and worsening prognosis of GDM [Finally, the increased intake of berries and leafy vegetables resulted in a significant increase of total serum antioxidant capacity in the nutrition intervention group at 6.3 ± 3.8 µmol/L while the nutrition education group’s total serum antioxidant capacity was 3.8 ± 3.5 µmol/L. The case–control study conducted by Parast et al. (2017) demonstrates that the total antioxidant capacity in women diagnosed with GDM was significantly lower than healthy pregnant women [The nutrition intervention group was also instructed to increase their postprandial physical activity via 15–30 min brisk walks after meals. Despite this guidance, there was no significant difference in the minutes per day spent walking, or any other physical activity, between the nutrition education and nutrition intervention groups. Although our study demonstrated that verbal instruction was not potent enough to result in a significant difference in postprandial physical activity in GDM patients, there have been RCTs that demonstrate the effectiveness of physical activity both in reducing GDM risk and for controlling active GDM. Hayashi et al. (2018) demonstrated in their RCT that an increase in walking during pregnancy to greater than 6000 steps per day was effective at lowering random glucose levels in patients with GDM [Overall, our clinical study has demonstrated that dietary counseling focusing on the addition of whole berries and leafy vegetables to the diets of pregnant women with GDM results in improved glycemic control and other metabolic and inflammatory parameters. As discussed previously, there is a plethora of research examining nutritional intervention in decreasing the risk of GDM development, but there is a lack of research regarding nutritional intervention during active GDM in advanced pregnancy. This research provides unique information that has not yet been reported and is increasingly beneficial to clinical practice and management of GDM. GDM, even well-controlled, has many risks for both the mother and the fetus, including complications during delivery such as shoulder dystocia and hypoglycemia in the newborn, as well as long-lasting effects, such as increased risk of developing type 2 diabetes or other cardiovascular diseases in the newborn later in life. Thus, having nutritional interventions that are shown to significantly improve the cardiometabolic markers of GDM during pregnancy are important to hopefully decrease the risk of these complications perinatally and beyond. Additionally, all of the participants included in our study are self-reported Hispanic women, one of the racial groups at the highest risk of both development of and complications from GDM, which allows the results of our study to be applied to those who may benefit the most from the interventions highlighted in this trial [However, we recognize some limitations of our study. Firstly, our intervention group was instructed to increase both whole berries and leafy vegetables, along with postprandial exercise, meaning that the significant changes in the various maternal metabolic parameters measured are the result of the combination of these different interventions. Thus, we are unable to isolate how much of a change is due to, for example, the berry intake or the postprandial exercise only, instead of the combination of these behaviors. Furthermore, the small sample size, while adequately powered for detecting differences in the various cardiometabolic and anthropometric endpoints measured, decreases the generalizability of the results to women with GDM from different ethnicities and risks, especially given that 100% of our population is from one specific ethnic group. Also, we did not measure specific blood markers of fruit and vegetable consumption, such as serum carotenoids and tocopherols. Finally, we examined outcomes in the mother, but did not examine fetal outcomes, infant birth weight and postpartum metabolic profiles. Despite these limitations, our findings fill a knowledge gap and contribute to the evidence on dietary and lifestyle interventions and their use in the management of gestational diabetes.