Diet and Gestational Diabetes: What the Guideline Recommends

After a gestational diabetes diagnosis, a dietary counselling appointment is usually the first thing on the agenda — even before any question of insulin. This is no coincidence: dietary adjustment is the first-line therapy with which, according to the DDG practice recommendation, most women can bring their blood glucose values into the target range.

Why Diet Is Central

The goal of nutritional therapy is to achieve near-normal blood glucose values, avoid ketosis and hypoglycaemia, support appropriate weight gain, and enable normal foetal growth. Importantly, the guideline states that recommendations must be tailored individually — to eating habits, daily schedule, weight, and sociocultural background. There is no single "GDM meal plan" that works the same way for everyone.

How Nutrients Should Be Distributed

As a rough guide, the guideline specifies:

• Carbohydrates: 40 to 50 percent of energy intake, not below 40 percent
• Protein: approximately 20 percent
• Fat: 30 to 35 percent

A moderate reduction in carbohydrate quantity can help blunt postprandial (post-meal) blood glucose spikes. More important than the sheer quantity is often the choice of foods: according to several studies cited in the guideline, foods with a lower glycaemic index are associated with better values and a lower need for insulin.

Why Breakfast Plays a Special Role

Insulin resistance is at its highest early in the morning, which is why blood glucose rises more steeply after breakfast than after lunch or dinner. For this reason the guideline recommends keeping the carbohydrate content of breakfast consciously lower than at later meals.

Meal Timing

Three reasonably sized main meals plus two to three smaller snacks spread throughout the day are recommended, including a small late-evening snack with a carbohydrate component. This late snack serves a specific purpose: it prevents an increase in ketone body production during the night.

What Else Is Important

• Adequate intake of folic acid, B-complex vitamins, calcium, vitamin D, magnesium, iron, and iodine
• Calorie-free sweeteners such as aspartame are safe during pregnancy within the permitted daily doses
• Weighing yourself weekly in the morning, fasting, without clothing, at home, as a guide to weight development

What Physical Activity Can Contribute in Addition

In addition to diet, the guideline recommends regular moderate physical activity — in its simplest form, brisk walking for at least 30 minutes on at least 3 days per week. A walk after a main meal can help reduce the subsequent rise in blood glucose.

An Important Reality Check

The evidence base and clinical practice do not always align here: several large controlled studies on diet and exercise as preventive measures were unable to demonstrate a reduction in GDM rates in certain risk groups, even though other outcomes improved (for example weight gain and caesarean section rates). This does not mean that dietary adjustment is ineffective, but rather that it should be viewed realistically: as the most important building block of treatment after diagnosis, not as a guarantee of preventing GDM in the first place.

This article does not replace individual dietary advice. Your specific nutrition planning should be carried out together with your practice or a qualified nutritionist.

Sources

Sources (secondary citations from the S3 guideline / DDG practice recommendation):

• Shepherd E, Gomersall JC, Tieu J, Han S, Crowther CA, Middleton P. Combined diet and exercise interventions for preventing gestational diabetes mellitus. Cochrane Database of Systematic Reviews 2017, Issue 11, Art. No. CD010443.
• Dodd JM, Turnbull D, McPhee AJ, et al. Antenatal lifestyle advice for women who are overweight or obese: LIMIT randomised trial. BMJ 2014;348:g1285.
• Poston L, Bell R, Croker H, et al. Effect of a behavioural intervention in obese pregnant women (the UPBEAT study): a multicentre, randomised controlled trial. Lancet Diabetes Endocrinol 2015;3(10):767–77.
• Moses RG, Barker M, Winter M, et al. Can a Low-Glycemic Index Diet Reduce the Need for Insulin in Gestational Diabetes Mellitus? A randomized trial. Diabetes Care 2009;32(6):996–1000.