Gestational Diabetes Mellitus
GDM is one of the most common complications of pregnancy. It affects approximately 18% of pregnancies in Australia and occurs when insulin resistance increases during gestation, resulting in elevated maternal blood glucose levels. It typically develops in the second or third trimester, when the body becomes naturally more insulin resistant. In some individuals, this leads to elevated blood glucose levels that require monitoring and management.
What is GDM?
GDM is defined as glucose intolerance first recognised during pregnancy—usually due to a mismatch between rising insulin resistance and the body’s ability to produce enough insulin.
You may be at increased risk of GDM if you:
Ethnicity: South Asian, Southeast Asian, Middle Eastern, Polynesian, Indigenous Australian, or Hispanic backgrounds are associated with higher baseline insulin resistance
Age: Over 30, especially over 40
Polycystic Ovarian Syndrome (PCOS) or family history of type 2 diabetes
History of GDM or macrosomic baby (>4.5 kg)
High BMI or early excessive weight gain
Medications: Corticosteroids or antipsychotics can impair glucose metabolism
Normal insulin changes during pregnancy
First trimester: Increased insulin sensitivity → may cause mild hypoglycaemia → contributes to nausea
Second trimester onward: Progressive insulin resistance is normal and adaptive to prioritise glucose for the feutus
Testing for GDM
Oral Glucose Tolerance Test (OGTT)
This is the standard diagnostic test for GDM, performed between 24–28 weeks gestation. If you are considered high-risk, your care team may recommend testing earlier (e.g. first trimester).
Test process:
Fast for 8–12 hours
Have a fasting blood glucose taken
Consume a 75g glucose drink
Blood is drawn again at 1 hour and 2 hours
Diagnostic Criteria (2020 guidelines):
Fasting: ≥ 5.1 mmol/L
1 hour: ≥ 10.0 mmol/L
2 hour: ≥ 8.5 mmol/L
Only one value needs to be elevated for diagnosis.
How to Prepare for the OGTT
To improve the accuracy of results:
Avoid low-carbohydrate or ketogenic diets in the 3–7 days prior. Maintain normal carbohydrate intake (~150g/day)
Avoid strenuous exercise the day before
Ensure adequate sleep and hydration
Do not consume caffeine the morning of the test
Prevention: Naturopathic Considerations
Prevention is most effective when implemented early (ideally preconception or in T1).
Key Nutrients:
Myo-inositol: Improves insulin sensitivity and reduces risk of gestational diabetes (GDM)
Magnesium (citrate or glycinate): Supports insulin signalling, reduces systemic inflammation, corrects deficiency commonly seen in pregnancy
Omega-3 (DHA): Improves metabolic markers, reduces inflammation, supports placental health
Vitamin D: Low levels linked to insulin resistance and GDM
Probiotics: Modulate the gut microbiome and support glucose metabolism
Strains: Lactobacillus rhamnosus & Bifidobacterium lactis
GDM Prevention
Dietary Principles to focus on:
Low-GI carbs: legumes, sweet potato, rolled oats, basmati rice, quinoa
Adequate protein: fish, eggs, legumes, tofu, organic meat
Healthy fats: olive oil, avocado, nuts, seeds
Non-starchy vegetables at every meal
Simple hacks:
Add vinegar or lemon before meals to slow glucose release
Don’t skip meals—eat every 3–4 hours
Avoid high GI foods and simple sugars: cakes, biscuits, juices and soft drinks.
Combine carbohydrates with protein and fat to slow glucose absorption
Macronutrient ordered eating (see below). Eat non-starchy vegetables and protein/fat before carbohydrates to blunt post-meal glucose spikes.
Nishano, et al., 2018
Movement:
Daily movement improves glucose uptake independently of insulin
20–30 minutes of walking, Pilates or resistance training most days
Avoid sedentary periods after meals—Walk after meals to lower post-meal glucose
Stress & Sleep:
Poor sleep and elevated cortisol contribute to insulin resistance
Aim for 7–9 hours of uninterrupted sleep
Support nervous system regulation with restorative practices e.g yin yoga, breathing, meditation
GDM Management
If diagnosed, GDM can usually be well-managed through dietary changes, daily movement, and sometimes medication. Blood glucose monitoring helps track how your body responds to food and lifestyle. The goal is to maintain glucose within target ranges to support optimal pregnancy outcomes.
Management includes:
Monitoring blood glucose levels
Nutrition support: structured meal plans with low-GI, high-fibre foods
Exercise: moderate daily movement
Medication (if required): insulin or oral medications under medical supervision
Naturopathic care can support this by:
Optimising nutrient status and glycemic control
Providing tailored diet and lifestyle strategies
Ensuring pregnancy-safe supplementation to optimise insulin function (e.g., magnesium, inositol, DHA)
Continued movement and stress support
Postpartum Follow-Up
GDM typically resolves after birth, but it’s important to follow up. A repeat OGTT or fasting insulin at 6–12 weeks postpartum helps identify if blood sugar levels have returned to normal. Long-term, lifestyle strategies remain important, as GDM increases your future risk of developing type 2 diabetes
GDM can feel overwhelming, but with the right support it is manageable—and often preventable. If you’re planning a pregnancy or currently navigating GDM, you don’t need to do it alone. Nutrition, lifestyle, and targeted nutrient support can make a significant difference for you and your baby.
Early intervention is always more effective than reactive treatment.
