Gestational diabetes mellitus (GDM) is the most common medical condition in pregnancy. Women* diagnosed with GDM and their offspring face increased short- and long-term risks.¹ Despite ongoing evolution of diagnostic criteria, medical nutrition therapy (MNT) remains the cornerstone of management. MNT involves an individualised plan, co-designed with a qualified dietitian, to meet nutritional needs, optimise glycaemia, and support recommended gestational weight gain (GWG). Physical activity complements dietary changes, and self-monitoring of blood glucose (SMBG) levels guides dietary adjustments and further treatment. Effective treatment of GDM improves pregnancy outcomes and may reduce future disease risk when dietary behaviours are sustained beyond pregnancy.^{2, 3} As such, nutrition plays a central role not only in short-term management but also as a foundation for longer-term health. 

Consensus recommendations for screening, diagnosis, and classification of GDM have recently been updated, with higher diagnostic thresholds and targeted early screening for women at increased risk.⁴ This change aims to minimise unnecessary medicalisation while focusing resources on those most likely to benefit from intervention.⁴ A diagnosis of GDM enables more tailored care, closer monitoring, and timely management.

Women’s experiences of a GDM diagnosis are often marked by emotional distress, including feeling overwhelmed, loss of autonomy, and concerns about over‑medicalisation. These challenges are compounded when information is inconsistent, not tailored, or culturally misaligned.⁴ Care that is personalised, coordinated, enabling, and delivered with dignity, compassion, and respect – through self‑management support, shared decision‑making, and collaborative care planning—improves engagement and adherence.⁵

Access to dietetic input remains inconsistent across Australia and Aotearoa New Zealand, with around 70–80% of women not receiving recommended dietetic care.⁶ Individualised dietary advice from a qualified dietitian is the strongest predictor of better maternal glycaemic control and infant birthweight (rather than the specific diet).⁷ 

There Is No Single “Best” Diet for GDM

Women with GDM have similar nutritional needs to other pregnant women. Historically, recommendations emphasised carbohydrate (CHO) restriction, but evidence indicates limited benefit from lowering total CHO unless intake is excessive.⁸ Changes to one macronutrient (e.g. lowering CHO) shift others (fat and protein), influencing insulin resistance, glycaemic control, and fetal growth. Lower‑CHO diets can reduce fibre and micronutrient intake and increase dietary fat, including saturated fat, which may worsen insulin resistance.⁵ Controlled crossover trials show women can meet glycaemic targets on higher-complex CHO/lower‑fat diets (~60% energy from CHO) with lower post‑prandial markers relative to lower‑CHO/higher‑fat patterns (~40% CHO).⁵ 

However, individual variability is significant. Wide confidence intervals in dietary trials outcomes highlight genuine differences in metabolic responses (e.g. gut microbiome, habitual diet, physical activity), underscoring the need to personalise dietary modification based on SMBG patterns, hunger, weight gain, and other clinical indicators rather than macronutrient ratios.⁷ 

Currently guidance consistently recommends at least 175g/day of carbohydrate in pregnancy to support fetal brain development and maternal metabolism, distributed across meals and snacks. ⁹ Dietary quality matters, with key principles to prioritise minimally processed, high fibre carbohydrates (wholegrains, legumes, fruit, vegetables); limit saturated fats, including unsaturated sources of fats; and ensure adequate protein. These principles are consistent with a Mediterranean dietary pattern with an overall emphasis on CHO quality, distribution across the day, and individualised tolerance.

Beyond glycaemia, maternal nutrition influences fetal programming and long-term health. Poor‑quality maternal diets, even without GDM, are associated with inadequate or excessive GWG, unhealthy birthweight, and increased lifetime risk of overweight, obesity, type 2 diabetes (T2D), and cardiovascular disease.3 With higher GDM diagnostic thresholds, stepping beyond one‑size‑fits‑all prescriptions to target individual risk and behavioural support is even more important.⁵  

The Australian Dietary Guidelines and the New Zealand Ministry of Health (Manatū Hauora) Guidelines provide evidence-based recommendations to support dietary quality in pregnancy (Table 1)

Table 1: The Australian Dietary Guidelines and the New Zealand Ministry of Health (Manatū Hauora) Guidelines provide evidence-based recommendations to support dietary quality in pregnancy

Behaviour Change: How Advice is Delivered Matters

Pregnancy is a considered teachable moment, for behaviour change when women are in contact with the health system and are generally more motivated to engage in health-enabling behaviours. However, intention does not automatically become sustained behaviour. Common barriers include pregnancy-related symptoms, competing priorities, and the demands of the postpartum period.¹⁰ Person‑centred, autonomy‑supportive counselling, positive framing, and shared decision making outperform restrictive or fear‑based messages.¹¹  

Effective interventions are:^{11, 12} 

• Tailored, grounded in behaviour‑change theory, and delivered by nutrition professionals.  

• Started early (<15 weeks’ gestation) with repeated contact. 

• Incorporate practical behaviour‑change techniques (e.g. action planning, rewards).  

• Aligned with women’s motivation to support baby’s health. 

A structured dietetic schedule (initial session within a week of referral; brief follow-ups at 1–3-week intervals; postpartum contact at 6–12 weeks) supports personalisation and continuity. Where group education increases access, individual follow-ups remain essential to refine plans, interpret SMBG patterns, and maintain engagement.⁵

Long‑term Risk Reduction Plan

Women who optimise GDM management generally achieve similar outcomes to those with normoglycaemia. However, even with optimal control, women with prior GDM have a ten‑fold higher risk of developing T2D, with 50–70% developing T2D within ten years.¹³ The revised diagnostic criteria may reduce GDM diagnoses, but many women (and their children) who no longer meet criteria still carry significant future metabolic risk.^{2, 3, 14} This shift offers an opportunity to broaden preventative care during pregnancy.  

Providing universal, flexible, equity-focused nutrition and physical activity support remains high-value care. Meta‑analyses and modelling suggest reductions in GDM (~33%), caesarean section (~7%), NICU admissions (~21%), and T2D (~10%), with returns on investment of up to $4.75 per dollar spent.15 Integrating universal low-intensity programs alongside targeted high-intensity pathways improves diet quality, physical activity, GWG, and referral rates in tertiary practice. 

Longer term nutrition and physical activity interventions with weight loss and moderate exercise can reduce T2D incidence by up to 58%, with real‑world programs achieving ~40% reduction at scale.¹⁶  Yet postpartum access to care and adherence are challenging.  

Antenatal care providers can help women and shift the system to support risk reduction by: 

• Reinforcing simple, sustainable behaviours (daily movement, fibre-rich meals, CHO distribution). 

• Addressing access to person-centred nutrition care and equity (cost, transport, childcare). 

• Normalising postpartum follow-up, with clear pathways to dietitian-led programs and flexible delivery. 

• Coordinating with GPs and community services to maintain momentum the momentum across the life course.  

*Women: The words woman and women are used throughout to reflect how most people who are pregnant identify. For this article, the term includes girls and people whose gender identity does not correspond with their sex at birth or who identify as non‑binary.