Research Report on Low-Energy Diet Intervention in Gestational Diabetes

Academic Background

Gestational Diabetes Mellitus (GDM) is a form of diabetes diagnosed for the first time during pregnancy, with a global incidence rate of approximately 6-15%. GDM not only increases the risk of short-term complications for both mothers and fetuses, such as large-for-gestational-age (LGA) infants and higher rates of cesarean sections, but also leads to long-term metabolic issues like type 2 diabetes and obesity in mothers and offspring. Although medical nutritional therapy is a cornerstone in the management of GDM, research on optimal energy intake remains very limited, particularly regarding whether energy restriction should be implemented during pregnancy. Evidence in this area is still insufficient.

In non-pregnant populations, low-energy diets have been shown to improve glycemic control in patients with type 2 diabetes and reduce medication requirements. However, the safety and efficacy of energy restriction during pregnancy remain controversial. Existing international guidelines are primarily designed for healthy pregnant women and have not been customized for those with diabetes or obesity. Therefore, this study aims to explore the safety and effectiveness of a low-energy diet in the management of GDM, particularly its impact on maternal weight changes, fetal birth weight, and metabolic outcomes.

Source of the Paper

This paper was authored by researchers including Laura C. Kusinski, from institutions such as the Leicester Diabetes Centre at the University of Leicester and the Institute of Metabolic Science at the University of Cambridge. The paper was published in February 2025 in the journal Nature Medicine, titled “Reduced-energy diet in women with gestational diabetes: the dietary intervention in gestational diabetes digest randomized clinical trial.”

Study Design and Process

Study Design

This study is a multicenter, randomized, double-blind, controlled clinical trial aimed at evaluating the effects of a low-energy diet in GDM patients. Participants were women with singleton pregnancies and a BMI ≥ 25 kg/m², randomly assigned to either a control group (2000 kcal/day) or an intervention group (1200 kcal/day). Dietary intervention started at enrollment (29 weeks) and continued until delivery, provided via weekly diet boxes. The primary endpoints were maternal weight change from enrollment to 36 weeks and standardized neonatal birth weight scores.

Study Population and Sample Size

A total of 425 GDM patients were recruited, with 211 assigned to the control group and 214 to the intervention group. Ultimately, data on maternal weight at 36 weeks were available for 388 participants (90.1%), and data on neonatal birth weight were available for 382 participants (89.8%).

Intervention Measures

The diet boxes were developed in collaboration with Mayfield Foods Ltd. The control and intervention groups received daily energy intakes of 2000 kcal and 1200 kcal, respectively, with macronutrient proportions of 40% carbohydrates, 25% protein, and 35% fat. During the study, the research team contacted participants weekly via email or telephone to assess adherence and satisfaction.

Data Collection and Analysis

Data collected included maternal weight, blood glucose (via continuous glucose monitoring, CGM), HbA1c, blood pressure, birth weight, and more. Data analysis used linear and logistic regression models, adjusting for baseline values and stratification by study center. Missing data were handled using multiple imputation methods.

Key Findings

Primary Endpoints

The study found no significant difference in maternal weight change at 36 weeks between the intervention and control groups (intervention effect: -0.20 kg, 95% CI: -1.01, 0.61; p > 0.1). Similarly, there was no significant difference in standardized neonatal birth weight between the two groups (intervention effect: 0.005, 95% CI: -0.19, 0.20; p > 0.1).

Secondary Endpoints

Although the primary endpoints did not show significant differences, the intervention group demonstrated a significant reduction in the need for long-acting insulin (control group: 39.2%, intervention group: 27.5%; OR: 0.36, 95% CI: 0.18–0.70; p = 0.003). Additionally, the intervention group had significantly lower HbA1c levels three months postpartum compared to the control group (β: -2.36 mmol/mol, 95% CI: -4.46, -0.26; p = 0.029).

Exploratory Analysis

Exploratory analysis of weight changes showed that 40% of the study participants achieved weight loss (average of 3 kg) during late pregnancy. Weight loss was associated with improved glycemic control (CGM time in range, TIR, increased by 7%), reduced systolic blood pressure, and a decreased rate of LGA infants (OR: 0.52, 95% CI: 0.29, 0.93; p = 0.027).

Conclusions and Implications

This study is the first to validate the safety and feasibility of a low-energy diet in GDM patients through a randomized controlled trial. Although the primary endpoints did not reach statistical significance, the low-energy diet significantly reduced the need for long-acting insulin and improved postpartum glycemic control. Furthermore, weight loss was associated with several beneficial health outcomes, including improved glycemic control, reduced rates of LGA infants, and better postpartum metabolic health.

These findings provide new insights into the clinical management of GDM, especially for pregnant women with a BMI ≥ 25 kg/m², where a low-energy diet can serve as a safe and effective intervention. Future research should further explore how to implement this intervention in clinical practice and evaluate its impact on long-term metabolic health.

Study Highlights

1. Innovative Intervention: This study is the first to systematically assess the effects of a low-energy diet in GDM patients, filling a gap in this field.
2. Multicenter Design: Conducted across eight centers in the UK, ensuring broad representation and reliability of results.
3. Double-Blind Randomized Controlled Trial: Through rigorous trial design, bias was minimized, enhancing the credibility of the results.
4. Exploratory Analysis: By analyzing the relationship between weight changes and health outcomes, the potential benefits of a low-energy diet were revealed.

Other Valuable Information

Limitations of this study include the relatively low proportion of non-white women in the sample and the impact of the COVID-19 pandemic on data collection. Despite these limitations, the study results hold significant clinical implications and provide direction for future research.